JP3051909B2 - Pattern film repair method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for correcting a pattern shape of a pattern film formed on a substrate. In particular, the present invention relates to a method and an apparatus for correcting a pattern shape of a pattern film of a photomask or a reticle.

[0002]

2. Description of the Related Art A conventional method for removing a predetermined pattern film by scanning and irradiating a focused ion beam on a predetermined area of a photomask surface will be described below. A method for correcting the pattern shape of a pattern film formed on a glass substrate as a sample using a focused ion beam in a vacuum chamber will be described. Ions are generated from an ion source, and the ions are converted into a focused ion beam having a spot diameter of submicron or less by an ion lens system. The focused ion beam is scanned and irradiated on a predetermined area of the photomask surface by the scanning electrode and the blanking electrode, secondary charged particles generated from the photomask surface by the irradiation are detected by the secondary charged particle detector, and the surface state of the photomask is detected. (Pattern shape) is displayed as an image on a display device. The pattern shape displayed on the display device is compared with a desired mask pattern shape, and a region from which the pattern film is removed is determined based on a difference between the shapes.
The scanning electrode and the blanking electrode are controlled so that the focused ion beam performs scanning irradiation in the pattern film removal area. Then, the removal area of the pattern film is repeatedly scanned and irradiated with the focused ion beam. Thereby, the removal area of the pattern film is formed by sputtering by ion beam irradiation.
Removed.

Here, since the sample, especially the substrate, is an insulating material, the surface of the sample is charged (positive potential) by irradiation of the focused ion beam, and the focused ion beam is charged by the charge and the charge of the ion beam. Is affected or the detection sensitivity of secondary charged particles generated from the sample surface is affected. In order to prevent charging, a region including the scanning region of the focused ion beam is irradiated with an electron beam to neutralize the charging of the sample surface.

At the same time as ion beam irradiation for sputtering, chlorine gas or carbon tetrachloride gas is sprayed from a nozzle onto an ion beam irradiation region, and the pattern film is removed by the action of ion beam irradiation and the etching gas. There is a method for increasing the area removal efficiency. This is called ion beam assisted etching.

[0005]

In order to accurately (shape) remove a pattern film formed on a substrate, first, a focused ion beam is scanned and radiated in a predetermined area.
It is necessary that the secondary charged particles generated by the irradiation be detected, and the pattern film shape obtained by the detected intensity be accurately and easily viewed. In particular, when the sample is a photomask or a reticle, the sample is based on the manufacture of a semiconductor integrated circuit, so that the shape accuracy of the correction must be good. At this time, the sample surface is prevented from being charged by the current electron beam irradiation, and an image based on the detection of secondary charged particles by the focused ion beam irradiation often cannot provide an easy-to-view image. It was difficult.

When the pattern film 30 is irradiated with the focused ion beam 5 while being repeatedly scanned, the chlorine film is blown and the ion beam assisted etching is performed to remove the pattern film in the removal region 30a. In particular, as shown in the cross-sectional view of FIG. 2, a groove is formed in the glass 31 which is a substrate of the edge portion 30b of the pattern film. In the case where the sample is a photomask, in the semiconductor integrated circuit manufacturing process, the light beam for exposure applied to the groove portion is undesirably refracted and causes a defective product.

[0007]

The present invention in order to solve the above problems SUMMARY OF THE INVENTION, at the same time repeatedly scanned to irradiate the pattern film in the region to remove modifying the focused ion beam, locally iodine gas vapors in the region, Alternatively, a pattern gas is removed by spraying a mixed gas of iodine gas and water vapor.

When a focused ion beam is scanned and irradiated on a predetermined area of the sample surface to detect secondary charged particles and display the image of the pattern film formed on the surface of the sample, the focused ion beam is irradiated. Simultaneously with irradiation, iodine vapor is locally sprayed on a predetermined area to detect secondary charged particles,
This is a method of displaying an image of a film based on the detected intensity and correcting the pattern film based on the image.

In order to achieve the above method, the apparatus of the present invention comprises an ion gun for generating ions, an ion lens system for converting the ions into a focused ion beam, and the focused ion beam on a predetermined region of a sample surface. A scanning electrode for deflecting scanning, a secondary charged particle detector for detecting secondary charged particles generated from the sample surface by irradiation of the sample with the focused ion beam, and a secondary charged particle signal formed on the sample surface based on the secondary charged particle signal. A display device for displaying an image of the pattern film, a nozzle for spraying iodine gas onto the focused ion beam irradiation area of the sample, and a difference between an image of the pattern film of the image display and a desired pattern shape of the pattern film. hand,
A pattern film correcting apparatus comprising a scanning region setting means for setting a scanning irradiation region of the focused ion beam.

[0010]

[Function] The amount of secondary charged particles emitted from the sample surface by irradiating the sample surface while scanning the focused ion beam increases due to the spraying of iodine gas performed simultaneously with the irradiation of the focused ion beam. The image display of the pattern film formed on the surface becomes clear. this is,
It is considered that the electric resistance of the glass substrate 31 is reduced by spraying the iodine vapor, and charge neutralization (neutralization) is performed. Therefore, the actual pattern film shape,
The comparison with the desired shape becomes easy and accurate. Correction processing of the pattern film can be performed accurately.

Further, by irradiation while scanning repeatedly a focused ion beam in a pattern film in the removal region, in removing the pattern film in the region, iodine vapor, or a mixed gas of iodine vapor and water vapor at the same time By spraying, the edge 3 of the removal area, particularly the edge 3 of the pattern film
No groove is formed in the glass substrate 31b as shown in the sectional view of FIG. This is presumably because the spraying of iodine vapor forms a protective film for glass substrate sputter etching. Therefore, in the process of manufacturing a semiconductor integrated circuit using this photomask, unwanted refraction of the exposure light beam applied to the groove as in the prior art did not occur, and the incidence of defective products was reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing preferred embodiments. FIG. 1 is a schematic sectional view of an apparatus for performing the method of the present invention. FIG. 1 does not show a focused ion beam irradiation system and a vacuum chamber for arranging a sample and the like in a vacuum. An ion source 1 for generating ions, particularly liquid metal ions, vertically downward is provided in the upper part in the vacuum chamber. A focusing lens 2 and an objective lens 3 forming an ion lens system are arranged around an axis where ions are generated, in order to focus the ions into a focused ion beam 5 having a submicron spot system. A blanking electrode 12 for stopping the irradiation of the sample 6 with the focused ion beam 5 and a scanning electrode 4 for deflecting and scanning the focused ion beam 5 are provided around the axis of the focused ion beam 5. ing. By appropriately controlling the blanking electrode 12 and the scanning electrode 4,
The focused ion beam 5 scans and irradiates an arbitrary predetermined region of the sample 6. The sample 6 is placed on an XY stage 7 for arbitrarily moving the sample 6 in the XY directions.

A secondary charged particle detector 9 for detecting secondary ions 8 as secondary charged particles generated from the focused ion beam irradiation position is disposed near the focused ion beam 5 irradiation position of the sample 6. The analog signal of the secondary charged particle detector 9 is converted into a digital signal by the A / D converter 10. Based on the digital signal, the A / D converter 10
The surface image of the sample 6 is displayed on the display device 11 connected to the.

Further, a storage container for storing iodine 33 is provided outside the vacuum chamber, and a heater 22 for evaporating the iodine 33 is provided outside the container. A tube 34 is connected to the storage container 23, and the tube 34 is introduced into the vacuum tank with the wall of the vacuum tank airtight. Tube 3
A nozzle 25 for locally spraying a gas (iodine 33 vapor) generated locally in the storage container to the sample irradiation position of the focused ion beam 5 is attached to the tip of the nozzle 4. The pipe 34 is provided with a valve 24 for turning on / off gas blowing. The gas blown from the nozzle 25 is provided for locally blowing the focused ion beam irradiation area on the sample surface.
Since the irradiation area of the focused ion beam is very small, and the inside of the vacuum chamber is in a vacuum, in fact, a considerably wider area is sprayed than the irradiation area of the focused ion beam 5. That is, the nozzle 25 is provided as a means for locally blowing gas to the irradiation area of the focused ion beam 5.

Next, the method of the present invention will be described. The ions generated from the ion source 1 are converted into an ion lens system (a focusing lens 2).
And a focused ion beam 5 by the objective lens 3). The focused ion beam 5 is irradiated by the scanning electrode 4 and the blanking electrode 12 while scanning a predetermined region of the surface of the sample 6 in which the pattern film 30 is formed on the surface of the substrate 31 made of glass. Secondary ions 8 which are secondary charged particles generated from the surface of the sample 6 by irradiation with the focused ion beam 5 are detected by a secondary charged particle detector 9.
An image of the pattern film 30 is displayed on the display device 11 based on the detected intensity of the secondary ions 8. The removal area of the pattern film 30 is set based on the difference between the image of the pattern film 30 and the desired pattern shape. The pattern film 3 set while locally spraying iodine 33 vapor from the nozzle 25 onto the set removal region of the pattern film 30.
Irradiation is performed while repeatedly scanning the focused ion beam on the zero removal region. The iodine 33 vapor is held in a solid state in the storage container 23, is vaporized by heating the iodine 33 with the heater 22, and the focused ion beam is emitted from the nozzle 25 through the pipe 34 and the valve 24. It is sprayed on the irradiation area. The pattern film 30a in the removal region of the pattern film 30 is removed by the repeated scanning irradiation of the focused ion beam and the spraying of iodine 33 vapor,
A pattern film 30 having a desired pattern shape is obtained. in this case,
When the pattern film 30 to be removed exists in a wide range of the sample 6, the above operation is performed at each place, and the pattern film 30 having a desired shape as a whole can be obtained.

When the focused ion beam 5 is repeatedly scanned and irradiated on the pattern film 30a to be removed, when the iodine 33 vapor is blown, iodine 3 is irradiated onto the irradiation area of the focused ion beam 5.
3 is adsorbed. By this adsorption, as shown in FIG.
No groove is formed in the edge portion 30b of the pattern film 30 of the removed pattern film 30a, and the pattern film 30a is removed flat. The reason for this is unknown, but it is sufficient for use as a photomask.

Further, when water vapor was mixed with the vapor of iodine 33 and sprayed on the focused ion beam irradiation region, an experimental result was obtained in which the surface of the glass substrate 31 from which the pattern film 30a was further removed was further flattened. As a method of mixing water vapor with iodine 33 vapor, water is stored together with iodine 33 in a storage container and heated by the heater 22 to obtain them.

Further, in order to display the pattern shape of the pattern film 30 on a display device, when a focused ion beam is scanned and irradiated on a predetermined area of the surface of the sample 6, iodine 33 vapor is blown from the nozzle to the area. Accordingly, the amount of detection of the secondary ions 8 generated from the surface of the sample 6 increases, and a clear image of the pattern shape of the pattern film 30 can be obtained. The reason is also unknown, but a very useful and very clear image can be obtained. Therefore, since the removal area of the pattern film 30 can be set with high accuracy, accurate correction can be performed.

[0019]

As described above, according to the present invention, the surface of the substrate after the removal of the pattern film becomes flat, the scattering of light in the subsequent exposure step is reduced, and the photomask can be corrected with high accuracy. . Further, since the detection amount of the secondary ions (charged particles) increases, the pattern shape of the pattern film can be obtained clearly, so that the correction area can be set with high accuracy.
Therefore, the photomask can be removed and corrected with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an apparatus using the present invention.

FIG. 2 is a partial sectional view of a sample for explaining the method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ion source 2 Focusing lens 3 Objective lens 4 Scanning electrode 5 Focused ion beam 6 Sample 7 XY stage 8 Secondary ion 9 Secondary charged particle detector 10 A / D converter 11 Display device 12 Blanking electrode 22 Heater 23 Storage container 24 Valve 25 Nozzle 30 Pattern film 31 Glass substrate 34 Tube

Claims (5)

(57) [Claims] In a vacuum chamber, ions generated from an ion source are converted into a focused ion beam by an ion lens system, and the focused ion beam is scanned by a scanning electrode onto a predetermined surface of a sample having a pattern film formed on a substrate surface. Irradiation while scanning the area, to detect secondary charged particles generated from the sample surface by the focused ion beam irradiation,
Displaying an image of the pattern film based on the detected intensity of the detected secondary charged particles, based on the difference between the image of the pattern film and the desired shape, set the removal area of the pattern film, the Irradiation is performed while repeatedly scanning the focused ion beam on the set pattern film removal area while locally spraying iodine vapor from a nozzle onto the set pattern film removal area, and the iodine vapor is in the pattern film removal area. A pattern film correction method for removing a pattern film. 2. In a vacuum chamber, ions generated from an ion source are converted into a focused ion beam by an ion lens system, and the focused ion beam is scanned by a scanning electrode onto a predetermined surface of a sample having a pattern film formed on a substrate surface. Iodine vapor is locally sprayed from a nozzle onto the predetermined area while scanning and irradiating the area, and secondary charged particles generated from the sample surface by the focused ion beam irradiation are detected, and the detected secondary charged particles are detected. Displaying an image of the pattern film based on the detected intensity of the pattern film, setting a removal area of the pattern film based on a difference between the image of the pattern film and a desired shape, and removing the removal area of the set pattern film. A pattern film correcting method for irradiating the focused ion beam while repeatedly scanning the pattern film to remove a pattern film in a removal region of the pattern film. 3. In a vacuum chamber, ions generated from an ion source are converted into a focused ion beam by an ion lens system, and the focused ion beam is scanned by a scanning electrode onto a predetermined surface of a sample having a pattern film formed on a substrate surface. Iodine vapor is locally sprayed from a nozzle onto the predetermined area while scanning and irradiating the area, and secondary charged particles generated from the sample surface by the focused ion beam irradiation are detected, and the detected secondary charged particles are detected. Displaying an image of the pattern film based on the detected intensity of the pattern film, setting a removal area of the pattern film based on a difference between the image of the pattern film and a desired shape, and locally controlling the iodine vapor from the nozzle. Irradiating the focused ion beam while repeatedly scanning the set pattern film removal area at the same time as spraying,
A pattern film correcting method for removing a pattern film in a removal region of the pattern film. 4. An ion gun for generating ions, an ion lens system for converting the ions into a focused ion beam, a scanning electrode for deflecting and scanning the focused ion beam on a predetermined area of a sample surface, and a sample for the focused ion beam A secondary charged particle detector for detecting secondary charged particles generated from the sample surface by irradiation, a display device for displaying an image of a pattern film formed on the sample surface based on the secondary charged particle signal, A nozzle for spraying iodine gas to the focused ion beam irradiation area, and a scanning irradiation area of the focused ion beam are set based on a difference between an image of the pattern film of the image display and a desired pattern shape of the pattern film. A pattern film correction device comprising a scanning area setting means. 5. In a vacuum chamber, ions generated from an ion source are converted into a focused ion beam by an ion lens system, and the focused ion beam is scanned by a scanning electrode onto a predetermined surface of a sample having a pattern film formed on a substrate surface. Irradiation while scanning the area, to detect secondary charged particles generated from the sample surface by the focused ion beam irradiation,
Displaying an image of the pattern film based on the detected intensity of the detected secondary charged particles, based on the difference between the image of the pattern film and the desired shape, set the removal area of the pattern film, the Irradiation is performed while repeatedly scanning the focused ion beam on the set removal region of the pattern film while locally spraying iodine vapor containing water vapor from a nozzle onto the removal region of the set pattern film. A pattern film correction method for removing a pattern film in a removal area.