JPS5899734A - Method and apparatus for inspecting photomask - Google Patents

Abstract

PURPOSE:To ensure the aptitude quality of a photomask as well as improve its production yield, by inspecting mask patterns after washing the mask surface while applying thereto a mechanical load of a desired intensity. CONSTITUTION:After a photomask 1 is brought above a washing means by a transfer mechanism, a mask-securing plate 10 is lifted up, and the mask 1 is transferred onto the securing plate 10. Then, the securing plate 10 is lowered to immerse the mask 1 in pure water 8 in the washing means. While ultrasonic vibrations are applied to the mask surface through a ultrasonic vibrator 16, the whole mask surface is scanned about two-three times by a rotary brush 15. Thereafter, the securing plate 10 is lifted up to the upper part of a washing vessel 8, and the mask 1 is transferred by the transfer mechanism located under the securing plate 10 to a stage 24 in a pattern inspecting means through a drying means to inspect the mask patterns, two by two, successively through optical microscopes 28a, 28b. Thus, all the photomasks having defective patterns not satisfying quality requirements can be judged to be failure.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an improvement in a photo mask inspection method and an improvement in a 7-oto-mask inspection apparatus.

(Shu Technology Background) The pattern strength required for photomasks varies depending on the purpose of use, i.e., whether it is used for contact exposure or projection exposure, and the frequency of use. The pattern strength also differs depending on the degree.

(Φ Follower technology and problems) On the other hand, in the conventional photomask manufacturing process, there is a means for comparing the mask pattern of a photomask after pattern formation with pattern drawing data, or a means for comparing with a reference pattern. After inspection using methods such as methods, cleaning was performed under certain conditions while applying mechanical loads such as brushing and ultrasonic waves to the pattern.Therefore, if the cleaning conditions were made severe, patterns would be damaged or defective after cleaning. However, if the cleaning load is made extremely light in order to eliminate the pattern damage defects, there is a problem in that the pattern strength required by the razor cannot be guaranteed.

OBJECT OF THE INVENTION The present invention provides a method for cleaning a mask surface by applying a mechanical load of a desired strength to ensure its quality, depending on the pattern's fineness, application, and frequency of use. We provide a photomask inspection method that inspects the mask pattern and removes defects before shipping immediately, and the equipment structure used in this inspection method, ensuring appropriate quality of the photomask and at the same time improving manufacturing yield. purpose.

(a) Structure of the invention, that is, the present invention is a method for processing photo-photographs after forming a mask pattern.
A method for inspecting a photo-mask, comprising the steps of washing the mask with water while applying rubbing force and ultrasonic waves to the mask surface, and then inspecting the washed photo-mask, and running water. Inside, a photo-i-splash cleaning means having a function of brushing the mask surface and a function of irradiating the mask surface with ultrasonic waves, and a photo-mask drying means are sequentially arranged in front of the photo-mask inspection means. The present invention relates to a photomask inspection device characterized by:

□□□Embodiments of the Invention The present invention will now be described in detail with reference to an apparatus configuration diagram of one embodiment shown in FIG. A schematic sectional view of the essential parts of the drying means in the same embodiment shown in Figure 4, and a mechanical load on the mask surface of the photomask that has completed the formation of the pattern inspection means in the same embodiment shown in Figure 4. It has a function of washing the photomask with water while applying water, a function of drying the photomask after washing with water, and a function of inspecting the photomask after drying. A first transport mechanism 3 for loading the mask 1 onto the cleaning gate 2, a cleaning means 2, a second transport mechanism 5 for transferring the photo mask from the cleaning means 2 to the drying means 4, and a drying means. 4, a third transport mechanism 7 for transferring the photomask 1 from the drying means 4 to the pattern inspection means 6, and the pattern inspection means 6.

The cleaning means 2 has a structure 15, for example, as shown in FIG. That is, a first mask holding stand 11 having a suction mechanism 10 is disposed at the bottom of a cleaning container 9 into which pure water 8 is poured. The mask holding base 11 has an airtight bearing 1
It can be freely moved up and down by a support tube 13 led out of the cleaning container 9 via a support tube 13. The upper part of the mask holding stand 11 has a structure that can be moved both horizontally and vertically via a support shaft 14, and has a function of brushing the patterned surface of the photo mask 1 fixedly mounted on the mask holding stand 11. A rotating brush 15 is provided. Furthermore, an ultrasonic vibrator 16 is disposed above the cleaning container 9 to radiate ultrasonic waves (US) toward the photomask 1.

In addition, the first stage (first prisoner 4) has a structure as shown in FIG. 3, for example. That is, a vacuum container 2 having a drain port 18 and a vacuum exhaust port 19 to which an automatic opening/closing valve 17 is connected.
0 and upper and lower 1. Can be moved horizontally! 21 forms a drying chamber, and a second mask holding stand 22 having a suction mechanism 10 is disposed at the bottom of the vacuum container 20. The second mask holding stand 22 is movable up and down by a support tube 13 led out of the vacuum vessel 20 via an airtight bearing 12, and is rotated at high speed to attract and hold it on the nuclear mask holding stand 22. The photomask 1 is then drained.

Further, the pattern inspection means (FIG. 1, 6) has a structure as shown in FIG. 4, for example. That is, an X-Y stage 24 having a mask holding mechanism (not shown) such as a suction mechanism and a light-transmitting window 23 in the center, and a light source 2 provided at the bottom of the X-Y stage 24 and a prism 26. and mirror 27g,
It has a normal structure mainly consisting of an illumination unit that has the function of irradiating 1 to 2 light beams from 27b, and a pair of microscopes 28a and 28b arranged on the top of the XY stage 24. For example, it has a pattern comparative inspection function for detecting defects in turns by sequentially superimposing two optical images of the photomask 1, which is formed by aligning a large number of similar patterns. Furthermore, a suction mechanism 1 is installed as an auxiliary mechanism in the preceding stage of the inspection function section.
a mask receiving mechanism 30 consisting of a third mask holding stand 29 which has a vertical axis and is movable up and down, and a mask extrusion mechanism 31 (32) of a normal structure that moves the mask 1 onto the X-Y stage 24. An extrusion direction arrow) is provided, and a photo and
A conventional mask scraping mechanism (not shown) is provided for removing the mask 1.

Furthermore, a first and a second
．． The third mask transport mechanism (Fig. 1, 3, 5゜7) is a transport mechanism that is commonly used in automatic processing equipment and has a structure that supports a photomask from the back side. ), a key-shaped mask carrying arm 34 having a suction/holding mechanism 33 is attached to the stage 3 with the support tube 35 as an axis.
6, and is held so as to be vertically movable and rotatable.

In the method of the present invention, for example, a photo mask inspection device as described above is used to inspect a photo mask after pattern formation.
Masks will be inspected.

That is, first, the photo mask is brought onto the cleaning means (FIG. 1, 2) by the first conveyor Vt*<FIG. 1, 3), and then the mask holding table (FIG. 2, 10) is raised to transfer the photo mask onto the mask holding stand 10, and then, as shown in FIG. Then, while irradiating the mask surface with ultrasonic waves via the ultrasonic transducer 16, the entire mask surface is brushed 2 to 3 times with the rotating brush 15.
[times] scanning.

At this time, the mechanical load applied to the mask surface by ultrasonic waves and brushing is, for example, 30±5 depending on the guaranteed quality of the photo mask.
(400 to 600 (W) at a frequency of about (KHz))
The desired output is selected within the range (the distance between the mask surface and the vibrator is about 10 (m)), and for the brushing load, nylon bristles with a thickness of 50 to 60 [μmφ] and a length of about 10 [simple] are selected. The number of revolutions was 9 in the rotating brush of about 10(i) used.
0-360 (r, l).

”] m Pressure force 5'O~10'0 (#), Roofing speed 1~5 (m/min.) The desired value is selected in the range of about 1000 m/min. Once the above cleaning process is completed, the rotating brush 15 from the upper part of the mask, then the mask holding stand 10 is raised to the upper part of the cleaning container 8, and the photo mask 1 is positioned at the lower part of the mask holding stand 10 (FIG. 1, 5). The photomask 1 is scooped up from the top of the mask holding table 10 which is lowered again by the mask carrying arm (FIG. 5, 34), and the second conveyance mechanism is rotated to transfer the photomask to the drying means (FIG. 1). 4) Place the mask on top. At this time, leave the lid of the vacuum container in the drying means out of the top of the container. Next, raise the second mask holding stand (FIG. 3, 22) provided in the drying means. : Pick up the photo mask from the second transport mechanism, and after removing the transport mechanism, lower the second mask holding stand, as shown in Figure 3.
After positioning the photo mask 1 in the bottom area of the vacuum container 20, the lid 21 is placed on the vacuum container 20, and the mask holding table 22 is rotated at 500 to 1000 (r, p, m) for several seconds. Drain the water from the photo mask, then place it in vacuum container 2.
0 to around 10"" (Torr-) for several tens of seconds
Evacuate and dry the photomask. When drying is completed, the lid 21 is removed from the top of the vacuum container 20, the second mask holding stand 22 is raised to the top of the vacuum container 20, and the third transport mechanism (FIG. 1, 7) After scooping up the photo-mask 1 using the same means as described above, the conveyance mechanism is rotated to transfer the photo-mask 1 to the upper part of the mask receiving mechanism 30 in the pattern inspection means shown in FIG. 4 (FIG. 1, 6). The mask holding base 29 of the mask receiving mechanism 30 is raised, the photo mask 1 is scooped up from the third transport mechanism, and the third transport mechanism is removed. The holding table 29 is lowered to a predetermined position, and then the photo mask 1 is pushed out by the mask pushing mechanism 31, and the photo mask 1 is fixed on the XY stage 24 as shown in the figure. While intermittently moving the X-Y stage 24, the same type of mask pattern formed on the photo mask 1 is examined using an optical microscope 28a.
, 28b, and are sequentially compared and inspected two by two.

In this pattern inspection means, the first pattern is inspected by superimposing the optical image of the standard pattern, which has been compared with the design pattern in advance, and the optical image of the first pattern. The optical image of the second pattern is superimposed on the optical image of the second pattern, and the second pattern is inspected. These operations are repeated in sequence to inspect all patterns on the photomask. This method is a conventional method. When the above inspection is completed, the photomask 1 is taken out from the X-Y stage 24 to the outside of the inspection means by a mask scraping mechanism (not shown), and the 7 photomasks for which the inspection has been completed are taken out as they are. Will be shipped.

#7 Effects of the Invention As explained above, in the present invention, a mechanical load is applied to the mask surface by brushing and ultrasonic waves in accordance with the required quality, taking into account the fineness of the photo mask, its purpose, frequency of use, etc. Since a pattern inspection is performed after cleaning while applying a high temperature, all photomasks that do not meet the required quality and have defective patterns are determined to be defective by the pattern inspection. Therefore, the shipping quality of the photomask is maintained at a sufficiently high quality.In addition, in the present invention, as mentioned above, the degree of mechanical load applied in the cleaning process is adjusted according to the required quality of the photomask. The manufacturing yield of 7-meter masks is improved without sacrificing additional quality.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of an apparatus according to an embodiment of the present invention, Fig. 2 is a schematic cross-sectional view of the main parts of the cleaning means in the same embodiment, and Fig. 3 is a main part of the drying means in the same embodiment. FIG. 4 is a schematic cross-sectional view of a main part of the pattern inspection means in the same embodiment, and FIG. 5 is a schematic top view (a) and a schematic cross-sectional view of the transport mechanism. In the figure, 1 is a photo mask, 2 is a cleaning means, 3 is a first transport mechanism, 4 is a drying means, 5 is a second transport mechanism, 6
is a pattern inspection means, 7 is a third conveyance mechanism, 8 is pure water,
9 is a cleaning container, 1o is a suction mechanism, 11 is a first i-sphere holding base, 12 is an airtight bearing, 13 is a support tube, 14 is a support shaft, 15 is a rotating brush, 16 is an ultrasonic vibrator, -17 is a Automatic opening/closing valve, 18 is a drain port, 19 is a vacuum exhaust port, 2
o is a vacuum container, 21 is a lid, 22 is a second mask holding stand,
23 is a transparent window, 24 is an X-Y stage, 25 is a light source, 2
6 is a prism, 27a, 27b are mirrors, 28, a, 2
8b is a microscope, 29 is a third mask holding stand, 31 is a mass extrusion mechanism, 32 is a mask extrusion direction arrow, and 33
34 is a mask holding arm, 35 is a support tube,
36 indicates a stage. 1st Flash 3rd (2) - 4th Flash 5th Flash

Claims (1)

[Claims] 1. A photomer that has finished forming a mask pattern;'
A method for inspecting a photo mask, comprising the steps of: washing the mask with water while applying frictional force and ultrasonic waves to the mask surface; and then inspecting the photo mask that has been washed with water. 2. A photomask cleaning means having a function of brushing the mask surface under running water and a function of irradiating the mask surface with ultraviolet waves, and a photomask drying means,
A photo machining inspection device characterized in that it is arranged sequentially in front of a mask inspection means.