JP2876650B2 - Beam diameter measuring device and beam diameter measuring reference body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a beam diameter measuring device.

[Conventional technology]

Conventionally, there has been a device that scans a photomask or a reticle for manufacturing an IC or an LSI with a laser beam, photoelectrically converts optical information from the foreign matter with a photoelectric converter, and detects a size of the foreign matter based on the photoelectric signal. It is known in Japanese Patent Application Laid-Open No. 60-237347.

In this type of apparatus, the detection sensitivity of foreign substances may be influenced by the beam diameter of the laser, and the beam diameter is measured to adjust the detection sensitivity to be constant.

An example of a conventional apparatus for measuring this kind of beam diameter will be briefly described with reference to FIG.

FIGS. 8 (a) and 8 (b) are views showing the side and plane of the configuration of the glass plate 1 and the photoelectric converter 4 on which a pattern for detecting optical information is measured when measuring the beam diameter.

As shown in FIG. 8 (b), a light-shielding layer indicated by oblique lines is formed on the surface of the glass plate 1, and a transparent slit portion 1a (which extends in the Y direction in FIG. The width d) in the X direction is formed.

FIG. 8A shows a configuration of the glass plate 1 and the photoelectric converter 4, and the photoelectric converter 4 is integrally attached to the glass plate 1.
When a beam scanned by a mirror or the like crosses the light-shielding layer of the glass plate 1 in the X direction, photoelectric conversion of light transmitted through the slit portion 1a of the beam is performed.

A method for measuring a beam diameter using this apparatus will be briefly described.

For example, when a beam irradiation spot (the diameter is assumed to be larger than the slit width d) moves on the glass plate 1 in the X direction at a speed v in FIG. 8B, light transmitted through the slit portion 1a is received. The photoelectric converter 4 outputs a photoelectric signal waveform as shown in FIG.

In FIG. 9, the vertical axis represents the output voltage obtained corresponding to the detected light intensity, and the horizontal axis represents the scanning time.

When measuring the beam diameter φ of the beam having the Gaussian intensity distribution, the photoelectric signal is measured at an intensity level V _e of 1 / e ² (where e is the base of natural logarithm) of the maximum value V 0 of the output voltage value in FIG. by slicing a waveform, measures the signal width Δt at level V _e, phi using a scanning velocity v of the beam is known in advance =
The beam diameter φ is obtained by calculating v × Δt.

[Problems to be solved by the invention]

However, according to the conventional technique, only one beam diameter in the X direction can be measured in one scan in the X direction (beam scanning direction) shown in FIG. 8, and the Y direction (direction intersecting the beam scanning direction) can be measured. In order to measure the beam diameter, it was necessary to provide a slit portion extending in the X direction in the light shielding layer of the glass plate 1 and scan the beam also in the Y direction.

For this reason, there is an inconvenience that a two-dimensional scanning mechanism is required for measuring the beam diameter, even though the beam scanning only needs to be one-dimensional due to the structure of the apparatus.

Further, since the scanning speed v is externally monitored using a drive signal of the beam scanning mechanism or the like, there is a disadvantage that an error is easily included.

The present invention has been devised in view of such conventional problems, and it is an object of the present invention to provide a measuring apparatus capable of measuring the beam diameter in the X and Y2 directions only by one-dimensional relative scanning.

[Means for solving the problem]

For this purpose, the present invention has a linear edge extending in a direction substantially perpendicular to the scanning direction, and in addition to the first pattern arranged side by side in the scanning direction, a certain angle with respect to the scanning direction. (In order to reduce the error, an angle of 10 ° to 80 ° is preferable.) A reference body formed by combining a second pattern having an edge extending in a direction is provided, and optical information from each pattern is photoelectrically converted. By calculating a value based on a photoelectric signal waveform corresponding to each of the first pattern and the second pattern and a predetermined interval value of the pattern, the beam diameter in two directions (a direction intersecting the scanning direction and the scanning direction) is calculated. Is what you want.

In particular, the beam diameter in the direction orthogonal to the scanning direction is a difference value between a value related to the time width obtained from the photoelectric signal waveform corresponding to the first pattern and a value related to the time width obtained from the photoelectric signal waveform corresponding to the second pattern. Is calculated based on

[Action]

In the present invention, a pattern orthogonal to the scanning direction,
By providing a reference body provided with two patterns oblique to the scanning direction, beam diameters in two directions can be obtained by one scan (one-dimensional scan).

〔Example〕

Next, the configuration of a beam diameter measuring apparatus according to a first embodiment of the present invention will be described with reference to FIG.

The glass plate 1 on which the predetermined pattern is formed and the photoelectric converter 4 are mounted on a stage (not shown) and are movable in the Y direction or the two-dimensional (X, Y) direction in FIG.

On the surface of the glass plate 1, a light-shielding layer indicated by oblique lines is formed, and the light-shielding layer has a width having a linear edge shown in the drawing.
The transparent slit portions P1 to P4 of d0 are formed at intervals d1, d2, and d3, respectively.

A laser beam 6 from a laser light source 2 is scanned on a glass plate 1 by a scanning mirror (vibrating mirror, polygon mirror, etc.)
The optical information scanned in the direction and transmitted through the slits P1 to P4 on the glass plate 1 is received by the photoelectric converter 4.

The signal photoelectrically converted by the photoelectric converter 4 is sent to a measurement / arithmetic processing circuit 5 and used for measuring the beam diameter.

2 (a), (b) and (c) are a side view, a plan view, and a photoelectric converter 4 showing the configuration of the glass plate 1 and the photoelectric converter 4 in the first embodiment of the present invention. FIG. 6 is a diagram illustrating an output voltage waveform obtained from the above.

As shown in FIG. 2 (b), one surface of the glass plate 1 is shielded from light by a chrome layer as shown by hatching, and four slit-like light transmitting portions P1 to P4 are formed in the chrome layer. .

The width of each of the slits P1 to P4 is a constant value d0,
It is assumed that the size is about 1/10 or less of the beam diameter to be measured, and the length of the slit in the longitudinal direction is sufficiently larger than the beam diameter.

The slits P1 to P4 have a reference line l parallel to the beam scanning line.
On the top, the center interval between the slits P1 and P2 is d1, the center interval between the slits P2 and P3 is d2, and the center interval between the slits P3 and P4 is d3, and d1 and d3 are arranged.
Are arranged so as to be equal (each center interval is defined on the reference line l).

The slits P1 and P4 are provided at angles of + 45 ° and −45 ° with respect to the reference line l (+ in the counterclockwise direction and clockwise in The slits P2 and P3 are arranged perpendicularly to the reference line l in order to obtain optical information on the beam diameter in the X direction in the figure.

As shown in FIG. 2 (a), the photoelectric converter 4 is integrally attached to the glass plate 1 on the surface opposite to the light shielding layer, and transmits the transmitted light from each of the slits P1 to P4. It is configured to receive light.

FIG. 3 is a simple block diagram of the processing circuit 5 of the present apparatus.

The signal from the photoelectric converter 4 is sent to an amplifier 7, and the amplified signal is converted by an analog-to-digital converter 8 (hereinafter referred to as “ADC 8”) in accordance with the cycle of a clock pulse from a pulse oscillator 9. The data is digitized at the sampling interval and stored in a memory (RAM) in the micro processing unit 10 (hereinafter, referred to as “MPU 10”).

In this case, it is assumed that data digitized for each pulse of the clock is stored in one address of the memory (RAM), and that the number of pulses corresponds to the number of addresses.

The MPU 10 measures and calculates necessary time intervals and time widths based on the signal waveform data stored in the memory (RAM), and stores the values as new data in the memory (RAM).

Then, the beam diameter is calculated based on the stored waveform data and the pattern intervals (supposedly stored) d0, d1, d2, d3, and the like, and the result is displayed on the display device 11.

FIG. 2 (c) shows a photoelectric signal waveform generated from the pattern when the beam is scanned on the reference line 1 at a constant speed v in the X direction in the figure.

Here, the vertical axis represents the output voltage obtained corresponding to the photoelectrically converted light intensity, and the horizontal axis represents the scanning time.

This photoelectric signal waveform is digitized by the processing circuit 5 and stored in a memory (RAM) as an output voltage value in response to a clock pulse.

The scanning time is determined by the period T of the clock pulse (for example, 1 μ
s) and the number of pulses are calculated.

Next, a method for obtaining the beam diameter will be described with reference to FIG.

<Step 101> Optical information from the slits P1 to P4 obtained by scanning the glass plate 1 with the laser beam light is photoelectrically converted by the photoelectric converter 4 and sent to the ADC 8 via the amplifier 7. .

At this time, it is assumed that the laser beam is initially set to scan on the reference line l.

<Step 102> The ADC 8 converts the output voltage from the amplifier 77 into a digital value for each clock pulse period T and sends it to the MPU 10.

The MPU 10 stores, at each address of a memory (RAM) in the MPU 10, data of a photoelectric signal waveform digitized according to a clock pulse.

Hereinafter, the processing of steps 103 to 105 is performed by the MPU 10, and it is assumed that each slit interval is stored in a memory (RAM) in the MPU 10 in advance.

<Step 103> Next, a beam scanning speed v is obtained.

MPU10 the second view (c) a slit P2, P3 photoelectric signal waveform S2, which is obtained than in, S3 corresponding to the maximum value V ₂ memory (RAM) on the two (hereinafter S2 waveform is. And S3 waveform) calculating the absolute value N ₁ of the address difference corresponding to the associated address.

Here, since the address and the clock pulses are taken corresponding such a configuration, the time interval t _b of the maximum value of the maximum value and S3 waveform S2 waveform, t than the period T of the address difference N ₁ and the clock pulse _b = N ₁ × T ‥‥ (1).

In this embodiment, since the beam has a Gaussian intensity distribution, the center interval d2 between the slits P2 and P3 stored in advance in a memory (RAM) and the time interval between the S2 waveform and the S3 waveform are used.
t _b has a corresponding relationship, and the beam scanning speed v can be obtained by calculating v = d2 / t _b ‥‥ (2).

 The value of v is stored in a memory (RAM).

<Step 104> Next, a beam diameter φ _X in the X direction is obtained.

The MPU 10 first calculates the slice voltage V _e2 for obtaining the beam diameter at which the intensity level is 1 / e ² (where e is the base of the natural logarithm) of the maximum value V ₂ of the S2 waveform and the S3 waveform is V _e2 = V ₂ × 1 / e ² ‥‥ (3)

Then, the MPU 10 obtains two addresses corresponding to the slice voltage V _e2 of the S2 waveform, obtains an absolute value N ₂ of the address difference, and then obtains N ₂
And the clock pulse period T, the time width t _{2 at} which the intensity level is 1 / e ² of the maximum value V ₂ of the S2 waveform is obtained from the calculation of t ₂ = N ₂ × T ‥‥ (4).

Further, the scanning speed v obtained in step 103 and the time width t ₂
By calculating φ _X = v × t ₂よ り (5), the beam diameter φ _X in the X direction is obtained.

The value of the diameter phi _X is stored in the memory (RAM).

Here, may seek diameter phi _X from but S3 waveform was determined diameter phi _X using S2 waveform, diameter phi _X obtained from the S2 waveform and S3
The configuration may be such that both the diameter φ _X obtained from the waveform is obtained and the average thereof is obtained.

<Step 105> Next, a beam diameter φY in the _Y direction is obtained.

First, as in step 104, the slice voltage V _e1 of the photoelectric signal waveforms S1 and S4 (hereinafter, referred to as S1 waveform and S4 waveform) is _calculated as V _e1 = V ₁ × _1/1 from the maximum value V ₁ of the S1 waveform and S4 waveform. It is obtained by calculating e ²求 め る (6).

Then, two addresses corresponding to the slice voltage V _e1 of the S1 waveform are obtained, the absolute value of the address difference is set to N _3, and N ₃ and the clock pulse period T are used to calculate 1 / e ² of the maximum value V ₁ of the S1 waveform. the time width t ₁ becomes intensity level obtained from the calculation of _{t 1 = N 3 × T ‥‥} (7).

Similarly, 2 corresponding to the slice voltage V _e1 of the S4 waveform
The difference between the two addresses is N _4, and from N ₄ and the clock pulse period T,
S4 obtained from the calculation of the maximum value V ₁ of the 1 / e ² of the time width t ₄ when made in the intensity level of the waveform _{t 4 = N 4 × T ‥‥} (8).

The S1 waveform and S4 waveform obtained from the patterns P1 and P4 include both the X-direction component and the Y-direction component of the beam diameter,
Here, T ₊ and T ₋ are calculated as (v × t ₁ + v × t ₄ ) / 2 = T ₊ ‥‥ (9) (v × t ₁ −v × t ₄ ) / 2 = T ₋ ‥‥ (10) And if the Y-direction component is φ _Y , an approximate expression Is calculated, the beam diameter φY in the _Y direction is obtained.

With the above steps, the beam diameters φ _X and φ _Y in the X and Y directions can be obtained.

Further, even when the beam diameter formed on the glass plate 1 is regarded as an ellipse and is slightly rotated with respect to the Y axis (the direction perpendicular to the scanning direction), the above approximate relational expression is satisfied;
The angle α between the major axis of the ellipse and the Y axis at that time is Becomes

According to the above embodiment, the beam diameter in the X direction and the Y direction is set to 1
It can be obtained simultaneously by one scan (one-dimensional scan).

Next, a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, a straight edge E1 is placed on the glass plate 1.
By forming the light-shielding patterns P5 to P7 indicated by oblique lines having the patterns E5 to E4, and by using the edges E1 to E4 of the respective patterns, the beam is emitted from the maximum-minimum value change portion of the photoelectric signal waveform obtained from the transmitted light. Find the diameter.

The overall configuration of the apparatus has the same configuration as that of the first embodiment, and the same members are denoted by the same reference numerals.

Light-shielding pattern P5 having a linear edge as shown
The glass plate 1 on which .about.P7 is formed and the photoelectric converter 4 are mounted on a stage (not shown), and are movable in the Y direction or two-dimensional (X, Y) directions in FIG. The laser beam 6 from the laser light source 2 is scanned in the X direction on the glass plate 1 by a scanning mirror (vibrating mirror, polygon mirror, etc.) 3, and the optical information transmitted through the non-light-shielding portions P 8 and P 9 on the glass plate 1 is Are received by the photoelectric converter 4.

The signal photoelectrically converted by the photoelectric converter 4 is sent to the measurement / arithmetic processing circuit 5 and used for measuring the beam diameter.

6 (a), (b), and (c) are obtained from the side view, the plan view, and the photoelectric converter 4 showing the configuration of the glass plate 1 and the photoelectric converter 4 in the embodiment of the present invention. FIG. 5 is a diagram showing an output voltage waveform obtained.

As shown in FIG. 6 (b), on one surface of the glass plate 1, light-shielding patterns P5 to P7 as shown by hatched portions having edges E1 to E4 are formed of chrome or the like. Light transmitting portions P8 and P9 are formed between them.

Each of the patterns P5 to P7 has a distance between the edges E1 and E2 (a'-
b ') is d4, and the distance between edges E2 and E3 (between b' and c ') is d.
5, the distance between the edges E3 and E4 (between c 'and d') is arranged to be d6, and d4 and d6 are arranged to be equal (each interval is a reference line l Defined above).

The length of each of the edges E1 to E4 is larger than the beam diameter.

The patterns P5 and P7 have the edges E1 and E4 at the angles of + 45 ° and −45 ° (counterclockwise, respectively) with the reference line l in order to obtain optical information on the beam diameters in the X direction and the Y direction in the drawing. The pattern 6 is arranged such that edges E2 and E3 are perpendicular to the reference line l in order to obtain optical information on the beam diameter in the X direction in the figure. Are located in

As shown in FIG. 6 (a), the photoelectric converter 4 is integrally attached to the glass plate 1 on the surface opposite to the surface on which the patterns P5 to P7 are formed, and each light transmitting portion P8 , P9.

FIG. 6 (c) shows a photoelectric signal waveform generated from the pattern when the beam is scanned on the reference line 1 in the X direction at a constant speed v.

Here, the vertical axis represents the output voltage obtained corresponding to the photoelectrically converted transmitted light amount, and the horizontal axis represents the scanning time.

V ₃ represents the maximum value of the transmitted light quantity, V ₄ represents a slice voltage is half of the amount of V _3.

In this embodiment, uses a beam diameter of Gaussian intensity distribution, and because the beam is scanned over the reference line l, a on sliced signal waveform at V _4, b, c, d point 6 (b), the intersections a 'between the edges E1 to E4 and the reference line l.
There is a correspondence with b ', c', d '.

Next, a description will be given of a method of obtaining a beam diameter by the configuration of the present embodiment.

As in the first embodiment, the photoelectric signal waveform from the photoelectric converter 4 is digitized and stored in a memory (RAM). The procedure for loading data into the memory (RAM) is as follows. It is assumed that the processing is performed by the same processing as steps 101 and 102 in the first embodiment.

Here, a procedure corresponding to the processing after step 103 in the first embodiment by the processing of the MPU 10 will be described with reference to FIG.

It is assumed that the edge intervals d4, d5, and d6 are stored in a memory (RAM) in the MPU 10 in advance.

First, the beam scanning speed v is determined.

MPU10, of the Figure 6 sliced value level V ₄ of the data in the memory (RAM) corresponding to the photoelectric signal waveform at (c), corresponding to the edge E2, E3 of FIG. 6 (b) moiety b, calculates the absolute value N ₅ of the difference between the two addresses of the memory (RAM) corresponding to the value of c.

Here, as in the first embodiment, the address and the clock pulse is assumed to be in correspondence, from the address difference N ₅ and the clock pulse period T, the interlevel bc sliced at level V ₄ the time interval t _d t _d = N × T ‥‥ (13)

And because we use a beam with Gaussian intensity distribution,
The edge interval d5 between b 'and c' in FIG.
t _d has a corresponding relationship, and the beam scanning speed v is obtained by the calculation of v = d5 / t _d ‥‥ (14).

Next, the beam diameter φ _X in the X direction is obtained.

Here, the time width (let it be tw) that is 1 / e ² of the maximum value of the light intensity of the beam, 10% of the maximum value of the transmitted light amount of the beam and
Obtained in advance the relationship between the time interval between the two points to be 90% (and tw _1), by correcting the time width tw ₁ in this relationship, the maximum value of the light intensity of the beam 1 / e ² Is converted to a time width for obtaining the beam diameter φ _X at.

Time width tw and tw ₁ it is determined from a Gaussian distribution curve type which is a relation of tw ≒ 1.56tw _1, this relationship value 1.56 is assumed to be previously stored in the memory (RAM).

Therefore, of the level-changing portion corresponding to the edge E2 of the photoelectric signal waveform of FIG. 6 (c), 10 of the maximum value V ₃ of the output voltage
Memory (RAM) corresponding to point b (1) at which the level becomes%
And address of, corresponding to the address of the memory (RAM) corresponding to b (2) point at which 90% of the level of the maximum value V _3, the absolute value N ₆ and the clock pulse period T from the edge of the difference (E2) Time width t ₆
Is obtained by the calculation of t ₆ = N ₆ × T ‥‥ (15), and the beam diameter φ _{X in the} X direction is corrected by correcting t ₆ with the relational value 1.56, so that φ _X = v × 1.56t ₆ ‥‥ (16) Is obtained from the calculation of

In this case, to determine the beam diameter phi _X from the level change portion corresponding to the edge E2, may be calculated beam diameter phi _X from the edge E3, also the beam diameter phi _X determined from the edge E2, E3 An average configuration may be used.

Then determine the Y direction of the beam diameter phi _Y.

In this case similarly to the case of obtaining the X-direction beam diameter phi _X, of the photoelectric signal waveform, corresponding to the edge E1, E4, beam time width between two points of 10% and 90% of the quantity of transmitted light
The values of t ₅ and t ₈ are obtained, and the values corrected by the relation value 1.56 are used to obtain Y ^{5 at} the light intensity of 1 / e ² of the maximum value of the light intensity of the beam.
And request the direction of the beam diameter phi _Y.

Here, the time widths t ₅ and t ₈ include both the component in the X direction and the component in the Y direction, and (v × 1.56t ₅ + v × 1.56t ₈ ) / 2 = T ₊ ‥‥ (17) (V × 1.56t ₅ −v × 1.56t ₈ ) / 2 = T ₋ ‥‥ (18) The component φ _{Y in the} Y direction can be obtained by the above approximate expression (11).

The beam diameter in the X and Y directions can be obtained by the above steps.

Even when the beam diameter is regarded as an ellipse and is slightly rotated with respect to the Y axis (the direction perpendicular to the scanning direction), the above approximate relational expression is satisfied.
The angle α formed with the axis is obtained from the approximate expression (12).

In the above two embodiments, the beam is scanned by a mirror or the like in the beam scanning method. However, similar results can be obtained by moving the beam diameter measuring device.

Next, a third embodiment of the present invention will be described with reference to FIG.

In the first embodiment, the beam diameter is obtained by photoelectrically converting the transmitted light from the transmission slits P1 to P4. In this embodiment, the reflection patterns P1 'to P4' are obtained.
The beam diameter is obtained by photoelectrically converting the reflected light.

The glass plate 1 on which the reflection patterns P1 'to P4' are formed is placed on the stage 12, and the direction of the white arrow in FIG.
Alternatively, it can be moved in a two-dimensional direction (a direction indicated by a white arrow and a direction perpendicular to the paper surface).

The laser beam 6 from the laser light source 2 is reflected by the beam splitter 13 and then irradiates the pattern substantially vertically.

The reflected light from the glass plate 1 due to the movement of the stage 12 and the pattern obtained by the relative scanning of the beam is received by the photoelectric converter 4 via the beam splitter 13, and the signal subjected to the photoelectric conversion is measured and processed by the measurement / operation processing circuit 5. And used for measuring the beam diameter.

The pattern according to the present embodiment forms the same pattern as the transmissive slit portions P1 to P4 in FIG.
The reflection patterns P1 'to P1 shown by oblique lines in FIG. 7 have a sufficiently higher reflectance than glass by treating the surface into a mirror surface.
4 ', which is constituted by making portions other than the reflection pattern into transmission components.

Detecting the photoelectric signal similar to that of the first embodiment based on the reflected light from the patterns P1 'to P4' and measuring the beam diameter in two directions by performing the same procedure as that of the first embodiment. Can be.

In the present embodiment, the beam and the glass plate 1 are scanned by moving the stage. However, the beam may be scanned by a scanning mirror or the like to detect reflected light from the pattern. Further, the digitization of the photoelectric signal is performed by responding to an up / down pulse (for example, one pulse every 0.01 μm) of a laser interferometer that measures the moving position of the stage 12 with a high resolution. It is preferable to increase or decrease the address.

According to the above embodiment, the beam spot diameters in the X direction and the Y direction can be obtained simultaneously by one scan (one-dimensional scan).

〔The invention's effect〕

According to the present invention, two patterns, a pattern extending in a direction orthogonal to the relative scanning direction of the glass plate and the beam and a pattern extending in a direction intersecting the scanning direction, are provided on the glass plate. The beam diameter in two directions, a scanning direction and a direction orthogonal to the scanning direction, can be measured by one scan (one-dimensional scanning), and the measurement time of the beam diameter can be reduced. The configuration of the device can be a one-way relative scanning mechanism.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the entire apparatus according to the first embodiment,
FIG. 2A is a side view showing a configuration of the glass plate 1 and the photoelectric converter 4 of the first embodiment, and FIG. 2B is a plane showing details of the glass plate 1 of the first embodiment. FIG. 2 (c) shows the first
FIG. 3 is a signal waveform diagram showing a signal waveform from the photoelectric converter 4 of the embodiment, FIG. 3 is a block diagram showing a processing circuit of the present invention, FIG.
FIG. 5 is a flow chart for obtaining the beam diameter in the first embodiment, FIG. 5 is a perspective view showing the entire apparatus according to the second embodiment, and FIG. 6 (a) is the glass plate 1 of the second embodiment. FIG. 6 (b) is a plan view showing details of the glass plate 1 of the second embodiment, and FIG. 6 (c) is a side view showing the configuration of the photoelectric converter 4 of the second embodiment. FIG. 7 is a side view showing the entire device of the third embodiment, and FIG. 8 (a) is a diagram showing a signal between the glass plate and the photoelectric converter 4 of the conventional example. FIG. 8 (b) is a side view showing the configuration, FIG. 8 (b) is a plan view showing details of a glass plate for measuring a beam diameter in a conventional example, and FIG. . [Description of Signs of Main Parts] 1 ... Glass plate 2 ... Laser light source 3 ... Scanning mirror 4 ... Photoelectric converter 5 ... Block diagram of processing circuit 6 ... Laser beam 7 ... Amplifier 8 ... Analog -Digital converter 9 ... Pulse transmitter 10 ... Micro process unit 11 ... Display device 12 ... Stage 13 ... Beam splitter P1 to P4 ... Slit-shaped transparent part E1 to E4 ... Linear edge

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01J 1/02 G01B 11/08

Claims (3)

(57) [Claims] 1. A radiation source for irradiating a beam having a predetermined diameter on a pattern formed in advance on an object surface, scanning means for relatively scanning the beam and the pattern, and optical information generated from the pattern by the scanning. And a photoelectric conversion unit for photoelectrically detecting the photoelectric conversion unit, wherein a beam diameter is measured based on a photoelectric signal of the photoelectric conversion unit, wherein at least two linear edges extending in a direction substantially perpendicular to the relative scanning direction are provided. A first pattern that is arranged side by side at a predetermined interval along the scanning direction and generates a signal that changes in level as the photoelectric signal according to the at least two edge positions by the relative scanning; Signal having an edge formed linearly in the direction indicated by the arrow, and changing the level as the photoelectric signal by the relative scanning in accordance with the edge position. A reference body provided with a second pattern to be generated out of the photoelectric signal, said first pattern of at least 2
A first value related to a time interval of a portion that changes in level corresponding to one edge position, and a second value related to a time width of a portion that changes in level corresponding to at least one edge position of the first pattern in the photoelectric signal. Measuring means for measuring a third value of the edge width of the second pattern in the photoelectric signal; and a third value based on the first value, the second value, and the third value. Calculating means for calculating the beam diameter in two directions of the relative scanning direction and a direction substantially orthogonal to the relative scanning direction. 2. The apparatus according to claim 1, wherein said arithmetic circuit calculates a beam diameter in a direction substantially orthogonal to said relative scanning direction based on a difference between said third value and said second value. The described device. 3. A reference body for measuring a beam diameter by beam scanning using a reference pattern formed in advance on an object plane, wherein the reference pattern is a straight line extending in a direction substantially perpendicular to a scanning direction. A first pattern having an edge and arranged in parallel along a scanning direction; and a second pattern having an edge extending at an angle to the scanning direction. Reference body.