JPH0750670B2 - Mask bonding apparatus and method of using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to X used for transferring a fine pattern with soft X-rays.
The invention relates to a device for adhering a reinforcing frame in a line mask and a method of using the same.

[Conventional technology]

As shown in FIG. 7A, the X-ray mask is composed of an absorber pattern 1, an X-ray transparent film 2 and a mask frame 3.
The absorber pattern 1 is made of Au having a thickness of about 0.5 to 1 μm that absorbs X-rays well, and the X-ray transparent film 2 transmits X-rays well.
It consists of a 2 μm thick SiN film. Alternatively, the mask frame 3 supporting the outer circumference of the X-ray transparent film 2 is made of a 380 μm thick Si substrate. Since such a conventional X-ray mask has a low rigidity of the mask frame 3, it has a drawback that workability such as flatness and handling is poor.

In order to solve this, a method of bonding and using a reinforcing frame to the X-ray mask has been used. An example of the bonding method (JP-A-53-75770) will be described with reference to FIG. 7 (b). First, an X-ray mask having the structure shown in FIG. 7A is formed. Next, the outer periphery of the X-ray transmission film 2 of the X-ray mask is placed on the one end surface 8 of the bonding jig 7 made of a hard material such as stainless steel. Next, a strong adhesive 6 such as epoxy is applied to one end surface 5 of the reinforcing frame 4 made of metal or the like and placed on the mask frame 3. Finally, they were pressed with a strong force for a long time to solidify and bond the adhesive 6.

[Problems to be solved by the invention]

However, the conventional bonding jig is a mere flat base for pressing the mask substrate and the reinforcing frame together when they are bonded to each other, and has no alignment function, flatness observation and correction function. As a result, it has been difficult to manufacture an X-ray mask having high flatness and high pitch accuracy. Further, the alignment mark formed in the mask used for the mask-wafer alignment is not limited to the movable range of the mark detection optical system in the X-ray exposure apparatus and is limited to, for example, within 500 μm. As is the condition that it must be within that tolerance. In the case of a reinforcing frame, the position from the outer circumference of the reinforcing frame must be within the allowable range.

With an X-ray mask with a reinforcing frame bonded using a bonding jig that does not have a conventional alignment function, the bonding position error is 500
Since it is as large as μm to 1 μm and has no reproducibility, it takes a long time to perform the coarse adjustment of the mask and an additional auxiliary alignment mechanism is required, which makes it difficult to perform the alignment efficiently. .

[Means for solving problems]

An object of the present invention is to provide a new mask bonding apparatus and a method of using the same which solves the problems of the conventional mask bonding jig, which cannot achieve high flatness, positional accuracy, pitch accuracy and productivity. Especially.

The main features of the present invention are that a positioning function for the X-ray mask and the reinforcing frame, a function for measuring the flatness of the X-ray mask, and a suction function for correcting and holding the flatness of the X-ray mask are provided. To do.

This is greatly different from the conventional technique in that the X-ray mask and the reinforcing frame can be easily bonded with high precision.

[Embodiment 1] FIG. 1 is a view for explaining a first embodiment of a mask bonding apparatus of the present invention, in which 11 is an X-ray mask mounting table, 12 is a suction mechanism, 13 is an escape hole, and 14 is A mark alignment optical system 15 is a flatness measuring optical system. In this mask bonding apparatus, the suction mechanism 12 provided on one end surface of the X-ray mask mounting table 11 fixes the mask substrate on which the absorber pattern or the like is formed, and adjusts the suction force to achieve flatness. It is for correcting bad X-ray masks. An escape hole 13 is provided inside the ring-shaped suction portion to prevent the center portion of the X-ray mask from being scratched or damaged. X-ray mask mounting table
Above the outer peripheral portion of 11, there is provided a mark alignment optical system 14 including an optical microscope or the like for performing alignment with the marks provided on the X-ray mask and the reinforcing frame. Also, X
Above the center of the line mask mounting table 11, a flatness measuring optical system 15 such as a Fizeau interference method is provided so that the flatness of the X-ray mask can be measured.

With reference to FIGS. 2 (a), (b) and (c), one embodiment of the bonding method using this device will be described. First, a plurality of alignment marks 17 are provided on the back surface of the X-ray mask 16 (FIG. 2 (a)),
Further, the reinforcing frame 18 is also provided with the corresponding alignment mark 19. Next, the X-ray mask 16 is placed on the vacuum chuck type suction mechanism 12 so that the absorber pattern forming portion of the X-ray mask 16 is located above the escape hole 3, and suction is performed.
Hold. Next, the flatness of the suction / holding X-ray mask 16 is measured by the Fizeau interference type flatness measuring optical system 15,
The flatness is corrected by adjusting the suction force.

Next, the reinforcing frame 18 made of quartz or the like is used as an X-ray mask.
It is placed on 16 and the alignment marks 17 and 19 of each other are detected and aligned by a mark alignment optical system 14 such as an optical microscope. Finally, an adhesive such as epoxy applied between each
Solidify 20.

As a result, even with an X-ray mask that has a warp of about 10 to 20 μm due to the initial warp of the Si wafer and the absorber pattern formation, the suction force is adjusted while feeding back the measurement results from the flatness measurement optical system. By doing so, the flatness can be easily and significantly improved. Further, the problem that the alignment mark of the X-ray mask has to be arranged with good reproducibility within the movable range of the coarse adjustment mark detection optical system can be sufficiently dealt with by providing the alignment function.

[Embodiment 2] FIGS. 3 (a) and 3 (b) show a second embodiment of the mask bonding apparatus of the present invention.
21 is an X-ray mask mounting table, 22 is a suction mechanism, 23 is an escape hole, and 24 is an outer peripheral abutment for aligning the mask substrate and the reinforcing frame. The component 25 is a flatness measuring optical system. In this embodiment, the outer peripheral abutting component 24 having the abutting reference surfaces 26 and 27 is arranged at the positions separated by the difference in the outer diameter between the X-ray mask and the reinforcing frame. First
The mask substrate and the reinforcing frame are aligned without using the mark alignment optical system as shown in the drawing. Specifically, as shown in Fig. 3 (b), the feature is that two-dimensional alignment can be easily performed by arranging the parts in a direction separated by 90 degrees and in the direction.

Needless to say, even if the abutting component 24 provided with each reference surface is further separated into components having individual reference surfaces and arranged on the X-ray mask mounting table, the same effect can be obtained. Also, it goes without saying that it is possible to use a cylindrical pin that has been accurately processed as the outer peripheral abutting component, or to arrange the abutting component in a positional relationship other than 90 °.

Next, one embodiment of a method for adhering an X-ray mask and a reinforcing frame using the present mask adhering device will be described with reference to FIGS. 4 (a) (b) (c).

First, on the outer periphery of the X-ray mask 31, as shown in FIG. 4 (a), a straight line portion 32 serving as a reference is provided at one place (32-1) or two places (32-1).
And 32-2). Similarly, the reinforcing frame 33 is also provided with one linear portion 34 (34-1) or two linear portions 34 (34-1 and 34-2) as shown in FIG. 4 (b).

Next, as shown in FIG. 4 (c), the X-ray mask 31 is placed on the X-ray mask placing table 21, and the X-ray mask 31 is placed on the reference surface 26 (26-1 and 26-2) of the outer peripheral butting component 24. Reference straight line part of line mask 32 (32
-1 and 32-2) are abutted to fix the position of the X-ray mask 31 and suck it. Next, the X-ray mask in the adsorption state
The warp state of 31 is measured by the flatness measuring optical system 25, and the flatness is corrected by adjusting the suction force according to the warp. Next, the reinforcing frame 33 is placed on the X-ray mask 31, and its reference straight line portion 34 is placed.
The reinforcing frame 33 is arranged at a desired position by abutting (34-1 and 34-2) on the other reference surface 27 (27-1 and 27-2) of the outer peripheral abutting component 24. Finally, the adhesive 35 applied between the X-ray mask and the reinforcing frame is solidified.

With such a structure, there is an advantage that it is not necessary to form alignment marks on the X-ray mask and the reinforcing frame. Further, while the alignment method using the mark alignment optics is a time-consuming operation, the outer peripheral reference butting method as in this embodiment has an advantage that the alignment can be performed in an extremely short time.

[Embodiment 3] FIG. 5 is a view for explaining a third embodiment of the mask bonding apparatus of the present invention, in which 41 is an X-ray mask mounting table, 42 is a suction mechanism, 43 is an escape hole, and 44 is A mark alignment optical system, 45 is a flatness measuring optical system, and 46 is an ultraviolet irradiation light source.

Since the third embodiment is a mask bonding apparatus in which the ultraviolet irradiation light source 46 is added to the first embodiment, other than that, the first embodiment (first
(Figure) is exactly the same.

The bonding method using the present mask bonding apparatus is the same as in the above-mentioned embodiment (second
It is essentially the same as the figure), but especially as a device that exerts a great effect when it is bonded to the X-ray mask with an ultraviolet curable adhesive, using a reinforcing frame made of quartz that transmits ultraviolet rays well. It is a proposal. For example, a quartz frame with a thickness of 2 to 5 mm is adopted as a reinforcing frame, UV-curable adhesive (L0-812) manufactured by Roctite Co. is used as an adhesive, and UV rays are emitted from a normal UV light source of 200 to 300 W. By doing so, solidification can be completed and bonding can be completed in a short time of 1 to 10 minutes. In contrast to conventional adhesives such as epoxy-based adhesives, which require fixing and holding for several hours to one day, there is a great advantage that the bonding time can be shortened to 1/10 to 1/100 or less of the conventional one. In addition, since the UV curable adhesive does not solidify at all unless it is irradiated with UV light, it is possible to take sufficient time to correct the flatness of the X-ray mask or align it with the reinforcing frame after applying the adhesive. There are advantages. The positions of the flatness measuring optical system 45 and the ultraviolet irradiation light source are not limited to the relationship shown in FIG. In fact, since it is difficult to operate both functions at the same time when they are vertically overlapped with each other, for example, the ultraviolet irradiation light source has a structure that can be rotationally moved on the sample surface only when necessary.

[Embodiment 4] FIG. 6 is a view for explaining a fourth embodiment of the mask bonding apparatus of the present invention, in which 51 is an X-ray mask mounting table, 52 is a suction mechanism, 53 is an escape hole, and 54 is An outer peripheral butting component for aligning the X-ray mask and the reinforcing frame, 55 is a flatness measuring optical system, and 56 is an ultraviolet irradiation light source.

The fourth embodiment is an example of a mask bonding apparatus that employs a positioning mechanism using an outer peripheral abutting component, instead of the positioning mechanism using the mark matching optical system of the third embodiment. As in the case of the third embodiment, the effect of being able to bond the mask substrate and the reinforcing frame in an extremely short time is added by adding the ultraviolet irradiation light source.

In the above description, the vacuum chuck method is used as the suction mechanism, but the vacuum chuck method is not limited to the vacuum chuck method. .

Further, in the description of the embodiments of the bonding method so far, an example in which a sample subjected to a membrane treatment by a back-etch is used as a mask substrate and a reinforcing frame is bonded thereto is illustrated, but the mask bonding device of the present invention is It is needless to say that the present invention is not limited to such a sample, and can be similarly used for a sample that is not back-etched.

〔The invention's effect〕

As described above, the mask bonding apparatus according to the present invention has a mechanism for measuring the flatness of the X-ray mask, a suction mechanism for controlling the force for sucking and holding the X-ray mask, and a position for the X-ray mask and the reinforcing frame. Since the X-ray mask reinforcing frame has a matching mechanism, there is an advantage that the X-ray mask reinforcing frame can be bonded with good flatness and high positional accuracy. The improved flatness also makes the flatness of the completed X-ray mask very good, and the gear gap between the mask and wafer can also be made small, enabling highly accurate pattern transfer with extremely small misalignment. The advantage is that Further, since the positional accuracy of the X-ray mask and the reinforcing frame is high, the positional error of the mask / wafer alignment mark from the outer periphery of the reinforcing frame can be easily suppressed within 50 μm. Since this error is a value that sufficiently satisfies the allowable value determined by the normal movable range of the mark detection optical system, there is an advantage that the coarse adjustment of the mask can be efficiently performed in a short time.

[Brief description of drawings]

FIGS. 1, 3 (a), (b), 5 and 6 are explanatory views of an embodiment of the mask bonding apparatus of the present invention, FIGS. 2 (a) (b) (c) and 4 Figure (a) (b)
(C) is an explanatory view of a reinforcing frame bonding method using the mask bonding apparatus of the present invention. 7 (a) and 7 (b) are views for explaining the problems of the conventional X-ray mask structure and the reinforcing frame bonding method. In the figure, 1 is an absorber pattern 2 is an X-ray transmission film 3 is a mask frame 4,18 and 33 is a reinforcing frame 5 is one end face of the reinforcing frame 6 is an epoxy adhesive 7 is a conventional adhesive jig 8 is an adhesive One end face of the jig 11,21,41 and 51 is the mask substrate mounting table 12,22,42 and 52 is the suction mechanism 13,23,43 and 53 is the escape hole 14 and 44 is the mark alignment optical system 24 and 54 is the outer circumference Abutting parts 15, 25, 45 and 55 are flatness measuring optical systems 16 and 31 are mask substrates 17 are alignment marks on the X-ray mask 19 are alignment marks on the reinforcing frame 20 and 35 are adhesives 26, 26 -1, and 26-2 are reference surfaces for abutting the X-ray mask provided on the outer peripheral abutting parts 27, 27-1 and 27-2 are reference surfaces for a reinforcing frame abutting provided on the outer peripheral abutting parts 32, 32 -1 and 32-2 are abutting reference surfaces 34,34-1 and 34-2 provided on the outer circumference of the X-ray mask, and the reference surface 34,34-1 and 34-2 are provided on the outer circumference of the reinforcing frame Abutting reference planes 46 and 56 are ultraviolet light sources.

Claims (5)

[Claims] 1. A mechanism for holding and adsorbing an X-ray mask with good flatness, a mechanism for aligning the X-ray mask with a reinforcing frame, and a mechanism for measuring the flatness of the X-ray mask. A mask bonding device. 2. The mask bonding apparatus according to claim 1, wherein the alignment mechanism is a mechanism for optically aligning marks. 3. The alignment mechanism is a mechanism for aligning the X-ray mask and the reinforcing frame by abutting the outer circumferences of the respective surfaces serving as the reference for each alignment. The mask bonding apparatus according to claim 1, wherein: 4. A mask bonding apparatus provided with a mechanism for holding and adsorbing an X-ray mask with good flatness, a mechanism for aligning the X-ray mask with a reinforcing frame, and a mechanism for measuring the flatness of the X-ray mask. 2. The mask bonding apparatus according to claim 1, further comprising an ultraviolet irradiation light source. 5. The flatness is improved by measuring the flatness of the X-ray mask and adjusting the force for adsorbing the X-ray mask, and the X-ray mask and the ultraviolet-transparent reinforcing frame are aligned with each other. A method for using a mask bonding apparatus, which comprises irradiating ultraviolet rays to an ultraviolet-curing adhesive applied between the two to solidify and bond them after the steps.