JP2011128376A - Method for adjusting output of laser device, laser device and inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for easily and accurately adjusting an output of a laser device that emits prescribed light by a sum frequency generating means using light beams at different wavelengths; and to also provide a laser device adjusting the output by the above method, and an inspection device having the laser device as a light source. <P>SOLUTION: A second nonlinear optical crystal 4 emits a laser beam at a wavelength of 266 nm. A third nonlinear optical crystal 8 emits a laser beam at a wavelength of 782 nm. These beams enter a fourth nonlinear optical crystal 11, where the beams are subjected to wavelength conversion by sum frequency generation to generate a light beam at a wavelength of 198.5 nm. Data of the angle of a reflection mirror 5, the angle of a wavelength selective reflection mirror 9 and the output of the laser beam at the wavelength of 198.5 nm measured in a measuring unit 13 are transmitted to a controller 14. The controller 14 adjusts angles of the reflection mirror 5 and of the wavelength selective reflection mirror 9 so that the maximum output is obtained. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an output adjustment method for a laser device, a laser device, and an inspection device.

  In recent years, the circuit line width required for a semiconductor element has become increasingly narrower as the large scale integrated circuit (LSI) is highly integrated and has a large capacity. The semiconductor element uses an original pattern pattern (a mask or a reticle, which will be collectively referred to as a mask hereinafter) on which a circuit pattern is formed, and the circuit is exposed and transferred onto a wafer by a reduction projection exposure apparatus called a stepper. Manufactured by forming. For manufacturing a mask for transferring such a fine circuit pattern onto a wafer, an electron beam drawing apparatus capable of drawing the fine pattern is used. Attempts have also been made to develop a laser beam drawing apparatus for drawing using a laser beam. The electron beam drawing apparatus is also used when drawing a pattern circuit directly on a wafer.

  By the way, an improvement in yield is indispensable for manufacturing an LSI that requires a large amount of manufacturing cost. However, as represented by a 1 gigabit class DRAM (Random Access Memory), the pattern constituting the LSI is about to be in the order of submicron to nanometer. One of the major factors that reduce the yield is mask pattern defects. With the miniaturization of the LSI pattern dimension formed on the semiconductor wafer, the dimension that must be detected as a pattern defect is extremely small. Therefore, a high inspection accuracy is required for an inspection apparatus that detects a defect in a transfer mask used in LSI manufacturing.

  One technique for detecting defects is “die-to-database inspection”. In this method, drawing data (design pattern data) is input to an inspection apparatus, design image data (reference image) is generated based on the drawing data, and is compared with measurement data (optical image) obtained by imaging the pattern. It is a technique. Here, the drawing data is obtained by converting CAD data with a pattern design into a format that can be input to the drawing apparatus.

  In die-to-database inspection, light emitted from a light source is irradiated onto a mask to be inspected via an optical system. The mask is placed on a table, and light irradiated as the table moves scans the mask. The light transmitted or reflected through the mask forms an image on the image sensor via the lens, and the optical image captured by the image sensor is sent to the comparison unit as measurement data. In the comparison unit, the measurement data and the reference data are compared according to an appropriate algorithm. If these data do not match, it is determined that there is a defect (see, for example, Patent Document 1).

  As the light emitted from the light source, light having a wavelength used by the stepper or a wavelength close thereto is used. For example, when a laser beam having a wavelength of 198.5 nm is used as inspection light, this light is obtained by superposing two laser beams having a wavelength of 782 nm and a wavelength of 266 nm to enter a nonlinear optical crystal and converting the wavelength (for example, (See Patent Documents 2 and 3.)

  Japanese Patent Application Laid-Open No. 2004-228688 generates a sum frequency from a fourth harmonic obtained by converting the wavelength of laser light having a wavelength of 1064 to 1065 nm and a second harmonic obtained by converting the wavelength of laser light having a wavelength of 1560 to 1570 nm. A method for generating a laser beam having a wavelength of 198.3 to 198.8 nm using the means is described.

  In order to obtain light of a predetermined wavelength with a desired output by such sum frequency generation, the superimposed light must be coaxially incident on the nonlinear optical crystal. For this reason, in the laser apparatus which is a light source, exact optical axis adjustment is needed. If the nonlinear optical crystal or optical element deteriorates due to laser light irradiation, or if a mechanical factor is added to the light source, the optical axis shifts and light with a desired output cannot be obtained. Therefore, the output must be adjusted by regular maintenance.

JP 2008-112178 A JP 2007-86101 A JP 2007-86104 A

The present invention has been made in view of these points. That is, an object of the present invention is to provide a method capable of easily and accurately adjusting the output of a laser apparatus that emits predetermined light using sum frequency generation means using light of different wavelengths.
Another object of the present invention is to provide a laser device capable of emitting predetermined light by means of sum frequency generation means using light of different wavelengths and adjusting the output easily and accurately, and using this laser device as a light source. It is in providing the provided inspection apparatus.

  Other objects and advantages of the present invention will become apparent from the following description.

In the first aspect of the present invention, the light having the wavelength λ ₁ is reflected by the first mirror and applied to the second mirror, and the light having the wavelength λ ₁ reflected by the second mirror and the second mirror are transmitted. The laser device that superimposes the light having the wavelength λ ₂ so as to be incident on the nonlinear optical crystal and generates the light having the wavelength λ ₃ that is the sum frequency light of the light having the wavelength λ _{1 and} the light having the wavelength λ ₂ by the nonlinear optical crystal. In the output adjustment method of
Measure the output change of light of wavelength λ ₃ when each angle of the first mirror and the second mirror is changed, and adjust each angle of the first mirror and the second mirror so that the output is maximized It is characterized by this.

In a first aspect of the invention, λ ₁ is 266 nm to 266.25 nm,
λ ₂ is 780 nm to 785 nm,
lambda ₃ is preferably 198.3Nm～198.8Nm.

A second aspect of the present invention includes a first light generating means for generating light of wavelength lambda _1,
Second light generating means for generating light of wavelength λ ₂ ;
A first mirror that reflects light of wavelength λ ₁ ;
A second mirror that reflects light of wavelength λ ₁ and transmits light of wavelength λ ₂ ;
A nonlinear optical crystal on which light having a wavelength λ ₁ reflected by the second mirror and light having a wavelength λ ₂ transmitted by the second mirror are incident;
A measurement unit for measuring the output of light of wavelength λ ₃ generated in the nonlinear optical crystal;
A controller that controls each angle of the first mirror and the second mirror;
Light of the wavelength lambda ₃ is the sum frequency light of the wavelength lambda ₁ of light and the wavelength lambda ₂ of light,
The control unit automatically changes each angle of the first mirror and the second mirror, receives information from the measurement unit, acquires the output change of the wavelength λ ₃ when each angle is changed, and the output is The present invention relates to a laser device characterized by adjusting each angle of a first mirror and a second mirror so as to be maximized.

In a second aspect of the invention, λ ₁ is between 266 nm and 266.25 nm,
λ ₂ is 780 nm to 785 nm,
lambda ₃ is preferably 198.3Nm～198.8Nm.

  According to a third aspect of the present invention, an optical image is obtained by irradiating the inspection target with light emitted from the laser device according to the second aspect of the present invention, and the optical image and the design data of the inspection target are created. The present invention relates to an inspection apparatus characterized in that a defect is detected by comparing with a reference image or another optical image obtained by irradiating the inspection object with the light.

  According to the first aspect of the present invention, there is provided a method capable of easily and accurately adjusting the output of a laser apparatus that emits predetermined light by means of sum frequency generation means using light of different wavelengths. .

  According to the second aspect of the present invention, there is provided a laser device capable of emitting predetermined light by means of sum frequency generating means using light of different wavelengths and adjusting its output simply and accurately.

  According to the third aspect of the present invention, the light source is provided with a laser device that emits predetermined light by means of sum frequency generation means using light of different wavelengths and can easily and accurately adjust its output. An inspection device is provided.

It is a block diagram of the inspection apparatus in this Embodiment. It is a conceptual diagram which shows the flow of the data in this Embodiment. It is a flowchart which shows an inspection process. It is a figure for demonstrating the acquisition procedure of an optical image. It is a figure explaining a filter process. It is a schematic block diagram of the optical system of the light source in this Embodiment. It is a flowchart which shows the output adjustment method of the laser apparatus of this Embodiment. It is an example which showed the relationship between the angle of the X direction of a 1st mirror, the angle of the X direction of a 2nd mirror, and the output of a laser beam. It is an example which showed the relationship between the angle of the Y direction of a 1st mirror, the angle of the Y direction of a 2nd mirror, and the output of a laser beam.

  FIG. 1 is a configuration diagram of an inspection apparatus according to the present embodiment. As shown in this figure, the inspection apparatus 100 includes an optical image acquisition unit A and a control unit B.

  The optical image acquisition unit A includes a light source 103, an XYθ table 102 that can move in the horizontal direction (X direction, Y direction) and the rotation direction (θ direction), an illumination optical system 170 that constitutes a transmission illumination system, and magnification optics. A system 104, a photodiode array 105, a sensor circuit 106, a laser length measurement system 122, and an autoloader 130 are included.

  In the control unit B, the control computer 110 that controls the entire inspection apparatus 100 has a position circuit 107, a comparison circuit 108, a reference circuit 112, a development circuit 111, an autoloader control unit 113, a bus 120 serving as a data transmission path, The table control circuit 114 is connected to a magnetic disk device 109, a magnetic tape device 115, a flexible disk device 116, a CRT 117, a pattern monitor 118, and a printer 119 as an example of a storage device. The XYθ table 102 is driven by an X-axis motor, a Y-axis motor, and a θ-axis motor controlled by the table control circuit 114. As these motors, for example, step motors can be used.

  Design pattern data serving as database-based reference data is stored in the magnetic disk device 109, read out as the inspection progresses, and sent to the development circuit 111. In the development circuit 111, the design pattern data is converted into image data (design pixel data). Thereafter, this image data is sent to the reference circuit 112 to be used for generating reference data.

  In FIG. 1, constituent elements necessary for the present embodiment are illustrated, but other known elements necessary for the inspection may be included.

  FIG. 2 is a conceptual diagram showing the flow of data in the present embodiment.

  As shown in FIG. 2, CAD data 201 corresponding to the drawing conditions of the present embodiment is converted into design intermediate data 202 in a hierarchical format such as OASIS. The design intermediate data 202 stores pattern data created for each layer and formed on the substrate. As described above, since the electron beam drawing apparatus 300 is not configured to directly read OASIS data, the OASIS data is converted into the format data 203 unique to each electron beam drawing apparatus for each layer and then converted into the electronic data. Input to the beam drawing apparatus 300. Similarly, the inspection apparatus 100 is not configured to directly read OASIS data, but is input after being converted into format data 203 compatible with the electron beam drawing apparatus 300. In some cases, data is input after being converted into format data unique to the inspection apparatus 100.

  By the way, the format data for drawing or inspection, or the OASIS data before conversion into these, maintains the auxiliary pattern for increasing the resolution of the pattern drawn on the mask, and the accuracy of the line width and the gap of the pattern. For this purpose, a figure for processing the pattern shape in a complicated manner is added. Therefore, the capacity of the pattern data is enlarged, and the electron beam drawing apparatus and the inspection apparatus are devised to prevent the stagnation of the drawing time and the inspection time. Specifically, a parallel processing computer capable of high-capacity and high-speed processing and a hard disk device designed to sufficiently cope with the read speed necessary for processing are combined with a mechanism portion that reads pattern data and develops data. Etc.

  FIG. 3 is a flowchart showing the inspection process.

  As shown in FIG. 3, the inspection process includes an optical image acquisition process (S202), a design pattern data storage process (S212), a development process (S214) as an example of a design image data generation process, and a filtering process ( S216) and a comparison step (S226).

  In the optical image acquisition process of S202, the optical image acquisition unit A of FIG. 1 acquires an optical image (measurement data) of the mask substrate 101. Here, the optical image is an image of a mask on which a graphic based on graphic data included in the design pattern is drawn. A specific method for acquiring an optical image is as follows, for example.

  A mask substrate 101 serving as an inspection sample is placed on an XYθ table 102 provided so as to be movable in the horizontal direction and the rotation direction by motors of XYθ axes. The pattern formed on the mask substrate 101 is irradiated with light from a light source 103 disposed above the XYθ table 102. More specifically, the light beam emitted from the light source 103 is applied to the mask substrate 101 via the illumination optical system 170. Below the mask substrate 101, an enlargement optical system 104, a photodiode array 105, and a sensor circuit 106 are arranged. The light that has passed through the mask substrate 101 forms an optical image on the photodiode array 105 via the magnifying optical system 104. Here, the magnifying optical system 104 may be configured such that the focus is automatically adjusted by an automatic focusing mechanism (not shown).

  FIG. 4 is a diagram for explaining an optical image acquisition procedure.

  As shown in FIG. 4, the inspection area is virtually divided into a plurality of strip-shaped inspection stripes 140 having a scanning width W in the Y direction, and each of the divided inspection stripes 140 is continuously scanned. Thus, the operation of the XYθ table 102 is controlled, and an optical image is acquired while moving in the X direction. In the photodiode array 105, images having a scan width W as shown in FIG. 4 are continuously input. Then, after acquiring the image on the first inspection stripe 140, the image on the second inspection stripe 140 is continuously input in the same manner while moving the image on the second inspection stripe 140 in the opposite direction. When an image in the third inspection stripe 140 is acquired, the image is moved in the direction opposite to the direction in which the image in the second inspection stripe 140 is acquired, that is, in the direction in which the image in the first inspection stripe 140 is acquired. While getting the image. In this way, it is possible to shorten a useless processing time by continuously acquiring images.

  The pattern image formed on the photodiode array 105 is photoelectrically converted by the photodiode array 105 and further A / D (analog-digital) converted by the sensor circuit 106. Sensors are arranged in the photodiode array 105. An example of this sensor is a TDI (Time Delay Integrator) sensor. The pattern of the mask substrate 101 is imaged by the TDI sensor while the XYθ table 102 continuously moves in the X-axis direction. Here, the light source 103, the magnifying optical system 104, the photodiode array 105, and the sensor circuit 106 constitute a high-magnification inspection optical system.

  The XYθ table 102 is driven by a table control circuit 114 under the control of the control computer 110, and can be moved by a drive system such as a three-axis (XY-θ) motor that drives in the X, Y, and θ directions. It has become. As these X-axis motor, Y-axis motor, and θ-axis motor, for example, step motors can be used. The movement position of the XYθ table 102 is measured by the laser length measurement system 122 and sent to the position circuit 107. The mask substrate 101 on the XYθ table 102 is automatically conveyed from the autoloader 130 driven by the autoloader control circuit 113, and is automatically discharged after the inspection is completed.

  Measurement data (optical image) output from the sensor circuit 106 is sent to the comparison circuit 108 together with data indicating the position of the mask substrate 101 on the XYθ table 102 output from the position circuit 107. The measurement data is, for example, 8-bit unsigned data, and represents the brightness gradation of each pixel.

  S212 in FIG. 3 is a storage step, and the design pattern data used when forming the pattern of the mask substrate 101 is stored in the magnetic disk device 109, which is an example of a storage device (storage unit).

  The figure included in the design pattern is a basic figure of a rectangle or a triangle. In the magnetic disk device 109, for example, information such as coordinates at a reference position of a figure, a side length, a figure code serving as an identifier for distinguishing a figure type such as a rectangle or a triangle, and the shape and size of each pattern figure The graphic data defining the position and the like are stored.

  Furthermore, a set of figures existing in a range of about several tens of μm is generally called a cluster or a cell, and data is hierarchized using this. In the cluster or cell, arrangement coordinates and repeated description when various figures are arranged alone or repeatedly at a certain interval are also defined. The cluster or cell data is further arranged in a strip-shaped region called a frame or stripe having a width of several hundreds μm and a length of about 100 mm corresponding to the total length of the photomask in the X direction or Y direction. .

  S214 in FIG. 3 is a development process. In this step, the development circuit 111 in FIG. 1 reads design pattern data from the magnetic disk device 109 through the control computer 110, and the read design pattern data of the mask substrate 101 is converted into binary or multivalued image data (design). Image data). Then, this image data is sent to the reference circuit 112.

  When design pattern data as graphic data is input to the expansion circuit 111, the expansion circuit 111 expands the design pattern data to data for each graphic, and displays a graphic code, a graphic dimension, and the like indicating the graphic shape of the graphic data. Interpret. Then, binary or multivalued design image data is developed as a pattern arranged in a grid having a grid with a predetermined quantization size as a unit. The developed design image data calculates the occupancy ratio of the figure in the design pattern for each area (square) corresponding to the sensor pixel. And the figure occupation rate in each pixel becomes a pixel value.

  S216 in FIG. 3 is a filtering process. In this step, the reference circuit 112 performs an appropriate filtering process on the design image data that is the image data of the sent graphic.

  FIG. 5 is a diagram for explaining the filter processing.

  The measurement data as an optical image obtained from the sensor circuit 106 is in a state in which the filter is activated by the resolution characteristic of the magnifying optical system 104, the aperture effect of the photodiode array 105, or the like, in other words, in an analog state that changes continuously. . Therefore, it is possible to match the measurement data by applying the filter process to the design image data which is the image data on the design side where the image intensity (the gray value) is a digital value. In this way, a reference image (optical data) to be compared with the optical image is created.

  The measurement data is sent to the comparison circuit 108 as described above. The design pattern data is converted into reference image data by the development circuit 111 and the reference circuit 112 and sent to the comparison circuit 108.

  The comparison circuit 108 compares the optical image obtained from the sensor circuit 106 with the reference image generated by the reference circuit 112 using an appropriate comparison / determination algorithm, and if the error exceeds a predetermined value, that portion is regarded as a defect. to decide. If it is determined as a defect, the coordinates, the sensor image (optical image) and the reference image that are the basis for the defect determination are stored as inspection results.

  The light source 103 is a laser device that generates light of a predetermined wavelength. And it is preferable that the light radiate | emitted from the light source 103 is the light of the wavelength used by a stepper, or a wavelength close | similar to this. In this embodiment mode, light having a wavelength of 198.5 nm is used as light emitted from the light source 103. This light can be obtained by superposing two laser beams having a wavelength of 782 nm and a wavelength of 266 nm to be incident on the nonlinear optical crystal and converting the wavelength.

  FIG. 6 is a schematic configuration diagram of an optical system of the light source 103.

  In FIG. 6, laser light having a wavelength of 1064 nm to 1065 nm is emitted from the first semiconductor laser 1. The second semiconductor laser 6 emits laser light having a wavelength of 1560 nm to 1570 nm.

The laser light emitted from the first semiconductor laser 1 which is the first light generating means is condensed by the first condenser lens 2 and then enters the first nonlinear optical crystal 3. As the first nonlinear optical crystal 3, for example, a KTP (KTiOPO ₄ ) crystal is used. The first nonlinear optical crystal 3 emits laser light having a wavelength of 532 nm to 532.5 nm as the second harmonic of the laser light having a wavelength of 1064 nm to 1065 nm. Laser light having a wavelength of 532 nm to 532.5 nm emitted from the first nonlinear optical crystal 3 is incident on the second nonlinear optical crystal 4. As the second nonlinear optical crystal 4, for example, a BBO (BaB ₂ O ₄ ) crystal is used. The second nonlinear optical crystal 4 emits laser light having a wavelength of 266 nm to 266.25 nm as the fourth harmonic of the laser light having a wavelength of 1064 nm to 1065 nm.

The laser light emitted from the second semiconductor laser 6, which is the second light generating means, is collected by the second condenser lens 7 and then enters the third nonlinear optical crystal 8. As the third nonlinear optical crystal 8, for example, an LBO (LiB ₃ O ₅ ) crystal is used. The third nonlinear optical crystal 8 emits laser light having a wavelength of 780 nm to 785 nm as the second harmonic of the laser light having a wavelength of 1560 nm to 1570 nm.

  The laser light having a wavelength of 266 nm to 266.25 nm emitted from the second nonlinear optical crystal 4 is reflected by the reflection mirror 5 that is the first mirror, and then is reflected on the wavelength selective reflection mirror 9 that is the second mirror. Irradiated diagonally. The wavelength selective reflection mirror 9 reflects the laser light having a wavelength of 266 nm to 266.25 nm, and transmits the laser light having a wavelength of 780 nm to 785 nm emitted from the third nonlinear optical crystal 8.

  The laser light having a wavelength of 266 nm to 266.25 nm reflected by the wavelength selective reflection mirror 9 and the laser light having a wavelength of 780 nm to 785 nm transmitted through the wavelength selective reflection mirror 9 are overlapped and proceed in the same direction, and the matching lens system After being matched at 10, the light enters the fourth nonlinear optical crystal 11, which is a sum frequency generating nonlinear optical crystal. As the fourth nonlinear optical crystal 11, for example, a BBO crystal is used. In the fourth nonlinear optical crystal 11, the laser light having a wavelength of 266 nm to 266.25 nm emitted from the matching lens system 10 and the laser light having a wavelength of 780 nm to 785 nm are sum-frequency mixed, and the wavelength is 198.3 nm to 198.8 nm. Becomes the laser beam. Thereafter, laser light having a wavelength of 198.3 nm to 198.8 nm is output from the laser device as parallel light by the collimator lens 12.

  The first to fourth nonlinear optical crystals are not limited to the above examples, and are transparent at each wavelength in wavelength conversion and phase-matched in each wavelength conversion process. Other crystals other than the above examples may be used.

  When a laser beam having a wavelength of 266 nm to 266.25 nm and a laser beam having a wavelength of 780 nm to 785 nm are incident on the fourth nonlinear optical crystal 11, the light may be incident on the same axis in order to maintain the phase matching condition. I need it. However, if optical elements such as nonlinear optical crystals, lenses and mirrors deteriorate due to laser light irradiation, or if mechanical factors are added to the light source, the optical axis will be displaced, making it impossible to obtain light with a desired output. . Therefore, it is necessary to adjust the output by regular maintenance.

  Here, as an output adjustment method, the optical axes of the laser light with a wavelength of 266 nm to 266.25 nm and the laser light with a wavelength of 780 nm to 785 nm are adjusted, respectively, and thereby the laser light with a wavelength of 198.3 nm to 198.8 nm It is conceivable to adjust the output.

  For example, first, a laser beam having a wavelength of 782 nm is guided to a photodiode by adjusting the optical path with two mirrors. Then, the angles of the two mirrors are adjusted so that the amount of laser light incident on the photodiode is maximized. Next, laser light having a wavelength of 266 nm is incident on the same photodiode. At this time, the angle of the other mirror is adjusted so that the amount of light having a wavelength of 266 nm is maximized with reference to the angle of one mirror adjusted at 782 nm.

  However, in the above method, since the optical axis adjustment is performed for light having a wavelength of 782 nm and light having a wavelength of 266 nm, even if light having a wavelength of 198.5 nm is emitted at the adjusted mirror angle, this is not necessarily the maximum output of the laser device. Is not limited. Moreover, in addition to adjusting the optical axis for each of the two lights to be overlapped, dedicated hardware is required for optical axis adjustment, so it takes time to start up and adjust, and the maintenance time is also long. It is.

  Therefore, as a result of intensive studies, the present inventor has reached the present invention. A method for adjusting the output of the laser apparatus according to the present embodiment will be described with reference to FIGS.

  FIG. 7 is a flowchart showing a method for adjusting the output of the laser device. In the maintenance of the laser device, the reflection mirror 5 and the wavelength selective reflection mirror 9 in FIG. 6 are shifted to obtain an optimum angle formed by these mirrors and the optical axis of the laser beam. That is, the laser beam having a wavelength of 266 nm to 266.25 nm reflected by the reflection mirror 5 and further irradiated to the wavelength selective reflection mirror 9 and then reflected by this mirror, and the wavelength 780 nm to the wavelength selective reflection mirror 9 transmitted. The output of the laser light having a wavelength of 198.3 nm to 198.8 nm generated by sum frequency mixing in the fourth nonlinear optical crystal 11 is maximized so that the laser light of 785 nm overlaps and proceeds in the same direction. Adjust the angles of these mirrors.

  Specifically, the mirror and the optical axis when the laser light having a wavelength of 266 nm to 266.25 nm emitted from the second nonlinear optical crystal 4 is applied to the reflection mirror 5 and reflected by the reflection mirror 5. Each angle between the mirror and the optical axis when the wavelength selective reflection mirror 9 is irradiated with laser light having a wavelength of 266 nm to 266.25 nm and reflected by the wavelength selective reflection mirror 9, In addition, the angle formed by the mirror and the optical axis when the laser light having a wavelength of 780 nm to 785 nm passes through the wavelength selective reflection mirror 9 is adjusted. These angles are defined by the optical axis, the X direction in the plane of each mirror, and the angle in the Y direction perpendicular to the mirror surface.

  In the output adjustment method of the laser device in the present embodiment, first, the wavelength of 198.3 nm to 198.8 nm is measured by the measurement unit 13 while changing the angle of the reflection mirror 5 in the X direction and the angle of the wavelength selective reflection mirror 9 in the X direction. Measure the output of the laser beam. And the angle of each X direction of the reflective mirror 5 and the wavelength selective reflective mirror 9 when an output becomes the maximum is calculated | required, and it is set as an optimal angle.

  FIG. 8 shows the X-direction angle of the reflection mirror 5 as the first mirror, the X-direction angle of the wavelength-selective reflection mirror 9 as the second mirror, and the output of the laser light having a wavelength of 198.5 nm. It is an example showing the relationship. In this example, the angle in the X direction (−85 mdeg) of the reflection mirror 5 and the angle in the X direction of the wavelength selective reflection mirror 9 (−932 mdeg) when the output reaches the maximum value (90.1 mW) are respectively optimum angles. Become.

  Subsequently, the output of laser light having a wavelength of 198.3 nm to 198.8 nm is measured by the measurement unit 13 while changing the angle of the reflection mirror 5 in the Y direction and the angle of the wavelength selective reflection mirror 9 in the Y direction. And the angle of each Y direction of the reflective mirror 5 and the wavelength selective reflective mirror 9 when an output becomes the maximum is calculated | required, and it is set as an optimal angle.

  FIG. 9 shows the angle in the Y direction of the reflection mirror 5 as the first mirror, the angle in the Y direction of the wavelength selective reflection mirror 9 as the second mirror, and the output of the laser beam having a wavelength of 198.5 nm. It is an example showing the relationship. In this example, the angle (−190 mdeg) in the Y direction of the reflecting mirror 5 and the angle (−473 mdeg) in the Y direction of the wavelength selective reflecting mirror 9 when the output reaches the maximum value (92.4 mW) are the optimum angles, respectively. Become.

  In the present embodiment, the angle of the mirror is optimized by the control device 14 of FIG. That is, the control device 14 automatically changes each angle of the reflection mirror 5 and the wavelength-selective reflection mirror 9, and acquires a change in the output of the laser light having a wavelength of 198.3 nm to 198.8 nm. That is, the angle of the reflection mirror 5, the angle of the wavelength selective reflection mirror 9, and the output of the laser light having a wavelength of 198.3 nm to 198.8 nm measured by the measurement unit 13 are respectively sent to the control device 14 and controlled. The apparatus 14 acquires the relationship as shown in FIGS. 8 and 9 and adjusts the angles of the reflection mirror 5 and the wavelength selective reflection mirror 9 so that the output is maximized. In the above example, the angle in the X direction of the mirror is adjusted and then the angle in the Y direction is adjusted. However, the order may be reversed.

  After adjusting the optimum angles of the reflection mirror 5 and the wavelength selective reflection mirror 9 as described above, the crystal temperature of the nonlinear optical crystal 11 is optimized as shown in FIG. If the output of laser light having a wavelength of 198.3 nm to 198.8 nm is not maximized even after adjusting the mirror angle, the above process is repeated again to adjust the mirror angle. As a result, the crystal temperature of each nonlinear optical crystal is optimized when the output value of the laser beam is maximized. On the other hand, when the output value of the laser beam does not become the maximum, the angle of the mirror is adjusted by switching to manual.

  After optimizing the crystal temperature of the nonlinear optical crystal 11, the maintenance of the laser device is finished.

  As described above, in the output adjustment method of the laser apparatus according to the present embodiment, the optical axes of the laser light with a wavelength of 266 nm to 266.25 nm and the laser light with a wavelength of 780 nm to 785 nm are adjusted, and thereby the laser apparatus Is adjusted while detecting the output of laser light having a wavelength of 198.3 nm to 198.8 nm that is actually oscillated, so that accurate output adjustment can be performed. The optical axis adjustment is performed by sending the mirror angle and laser beam output to the control device and adjusting the mirror angle so that the output is maximized by the control device, so no dedicated hardware is required. . Therefore, output adjustment can be performed easily and in a short time.

  The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, an example in which laser light having a wavelength of 198.3 nm to 198.8 nm is emitted by sum frequency generation using laser light having a wavelength of 266 nm to 266.25 nm and laser light having a wavelength of 780 nm to 785 nm. However, the present invention is not limited to the above wavelengths. The present invention can be applied to any laser apparatus that emits predetermined light by means of sum frequency generation means using light of different wavelengths.

  In the above embodiment, the die-to-database method has been described as an example. However, the defect inspection method may be a die-to-die method. That is, the inspection apparatus of the present invention may detect defects by comparing optical images acquired by irradiating the inspection object with light emitted from the laser apparatus of the present invention.

  Furthermore, in the above-described embodiment, descriptions relating to the device configuration and control method that are not directly required for the description of the present invention are omitted, but it is needless to say that the required device configuration and control method can be appropriately selected and used. Yes. In addition, all inspection apparatuses or inspection methods that include the elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 100 Inspection apparatus 101 Mask board | substrate 102 XY (theta) table 103 Light source 104 Enlargement optical system 105 Photodiode array 106 Sensor circuit 107 Position circuit 108 Comparison circuit 109 Magnetic disk apparatus 110 Control computer 111 Expansion circuit 112 Reference circuit 113 Autoloader control part 114 Table control circuit 115 Magnetic tape unit 116 Flexible disk unit 117 CRT
118 Pattern Monitor 119 Printer 120 Bus 122 Laser Measuring System 130 Autoloader 170 Illumination Optical System 201 CAD Data 202 Design Intermediate Data 203 Format Data 300 Drawing Device 1 First Semiconductor Laser 2 First Condensing Lens 3 First Nonlinear Optical Crystal 4 Second nonlinear optical crystal 5 Reflecting mirror 6 Second semiconductor laser 7 Second condenser lens 8 Third nonlinear optical crystal 9 Wavelength selective reflecting mirror 10 Matching lens system 11 Fourth nonlinear optical crystal 11
12 Collimator lens 13 Measuring unit 14 Control device

Claims (5)

The light of wavelength λ ₁ is reflected by the first mirror and irradiated to the second mirror, the light of wavelength λ ₁ reflected by the second mirror and the light of wavelength λ ₂ transmitted by the second mirror Is made to enter the nonlinear optical crystal, and the nonlinear optical crystal generates light of wavelength λ ₃ which is the sum frequency light of the light of wavelength λ _{1 and} the light of wavelength λ _2. In the method
The change in the output of the light having the wavelength λ ₃ when each angle of the first mirror and the second mirror is changed is measured, and the first mirror and the second mirror are set so that the output becomes maximum. A method for adjusting the output of a laser device, characterized in that each angle of the laser is adjusted. λ ₁ is between 266 nm and 266.25 nm,
λ ₂ is 780 nm to 785 nm,
output adjusting method of a laser apparatus according to claim 1 lambda ₃ is characterized in that it is a 198.3Nm～198.8Nm. First light generating means for generating light of wavelength λ ₁ ;
Second light generating means for generating light of wavelength λ ₂ ;
A first mirror that reflects the light of wavelength λ ₁ ;
A second mirror that reflects the light of wavelength λ ₁ and transmits the light of wavelength λ ₂ ;
A nonlinear optical crystal on which the light having the wavelength λ ₁ reflected by the second mirror and the light having the wavelength λ ₂ transmitted through the second mirror are incident;
A measurement unit for measuring the output of light of wavelength λ ₃ generated in the nonlinear optical crystal;
A controller that controls each angle of the first mirror and the second mirror;
The light having the wavelength λ ₃ is a sum frequency light of the light having the wavelength λ _{1 and} the light having the wavelength λ ₂ .
The control unit automatically changes each angle of the first mirror and the second mirror, receives information from the measurement unit, and changes the output of the wavelength λ ₃ when the angle is changed. And adjusting each angle of the first mirror and the second mirror so that the output is maximized. λ ₁ is between 266 nm and 266.25 nm,
λ ₂ is 780 nm to 785 nm,
4. The laser device according to claim 3, wherein [lambda] ₃ is 198.3 nm to 198.8 nm.   An optical image is obtained by irradiating the inspection target with light emitted from the laser device according to claim 3, and the reference image or the light created from the optical image and design data of the inspection target is used as the optical image. An inspection apparatus for detecting a defect by comparing with another optical image obtained by irradiating an inspection object.