JP2894772B2 - X-ray window manufacturing method - Google Patents

Description

Description: Object of the Invention (Industrial application field) The present invention relates to a method for manufacturing an X-ray window, and more particularly to a method for manufacturing an X-ray extraction window of an X-ray transfer apparatus.

(Prior Art) In recent years, as the demand for higher density and higher integration of semiconductor integrated circuits has increased, research and development of a lithography technique for forming a pattern on a photosensitive agent has been rapid among fine processing techniques for circuit patterns. Showing progress.

At present, photolithography technology using light as the exposure medium is the mainstream in mass production lines, but the resolution is approaching its limit, and as an alternative to this photolithography technology, X-ray lithography in which the resolution is dramatically improved in principle Technology research and development is making rapid progress.

In the X-ray lithography, unlike the exposure method using light, there is currently no technique for transferring a predetermined pattern by reducing it. For this reason, in the X-ray exposure, an X-ray exposure mask on which a predetermined pattern is formed and a sample are held in parallel at an interval of about 10 μm, and X-rays are irradiated through the X-ray mask to thereby expose the surface of the exposure target. A 1: 1 transfer method for forming a transfer pattern is adopted.

In this 1: 1 transfer method, since the transfer accuracy of the pattern of the X-ray mask becomes the device accuracy as it is, it is essential to perform uniform illumination.

By the way, since X-rays are generated under vacuum,
A partition is provided between the vacuum region of the radiation source and the transfer region, and the transfer region is provided with X-rays through an X-ray transparent window (hereinafter referred to as an X-ray window) provided on the partition. Is to be guided.

As the X-ray window, a beryllium (Be) thin film is usually used. The Be thin film may cause non-uniformity in the intensity of X-rays transmitted by surface irregularities due to the processing accuracy.

Therefore, in order to reduce the non-uniformity, a method of improving the uniformity of the transmitted X-ray intensity by mechanically scanning the X-ray window made of the Be thin film with respect to the X-ray has been proposed. (1989, 26th Spring Applied Physics Society 4a
-K-6,4a-K-7).

However, it is necessary to provide a scanning mechanism in order to vibrate a thin film having at least one side in a vacuum region with an amplitude equal to or greater than the amplitude at which unevenness of the thin film is made uniform. Also, the scanning portion and the X-ray source portion must be connected by an operable component such as a bellows. This problem is not limited to the Be thin film, and is a common problem when a resin thin film or the like is used as the X-ray window.

(Problems to be Solved by the Invention) As described above, the conventionally used X-ray window requires a mechanical scanning mechanism to obtain uniform transmittance.
There is a problem that a large amount of equipment is required.

The present invention has been made in view of the above circumstances, and does not require a mechanical scanning mechanism, and has a uniform X-ray transmittance.
The purpose is to provide line windows.

[Configuration of the invention]

(Means for Solving the Problems) Therefore, in the present invention, a negative type X-ray photosensitive agent film is formed on the surface of the X-ray window material film, X-ray exposure is performed from the X-ray window material film side, and development processing is performed. An X-ray photosensitive agent film pattern is selectively provided in a region having a high line transmittance.

(Operation) According to the method of the present invention, an exposure process is performed on the photosensitive material film depending on the transmission nonuniformity of the X-ray window material film, and a photosensitive material film pattern corresponding to the transmitted X-ray amount is formed. Therefore, the photosensitive material film pattern is left in the region of the X-ray window where the X-ray transmittance is large, and the remaining photosensitive material film pattern functions as an absorber for X-rays. By matching the photosensitive characteristics, it is possible to reduce the transmission non-uniformity of the X-ray window. This method is a very simple method.

Further, the X-ray window material film may be etched using the X-ray photosensitive agent film pattern as a mask. That is, a negative type X-ray photosensitive agent film is formed on the surface of the X-ray window material film,
X-ray exposure from the X-ray window material film side
An X-ray photosensitive agent film pattern is selectively provided in a region having a large X-ray transmittance, and further, the X-ray window material film is etched using the X-ray photosensitive agent film pattern as a mask, and then the X-ray photosensitive agent film pattern is peeled off. As a result, the X-ray window material film in the region where the X-ray transmittance is small is thinned, and the X-ray transmittance is increased.
An X-ray window having a uniform X-ray transmission amount can be provided. This method requires more man-hours than the above method, but improves the mechanical strength of the surface while leaving the photosensitive material film pattern as it is.

Further, by repeating this step, or by performing the same treatment on both surfaces, a greater effect can be obtained.

The X-ray used for exposure at the time of forming the X-ray window does not need to have the same wavelength as the wavelength of the X-ray source using the X-ray window. It is possible to match the photosensitive characteristics of the material film, and to obtain an X-ray window with higher uniformity.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Example 1 First, as shown in FIG.
A 30 μm Be thin film 1 is formed. This Be thin film 1 is not uniform in film thickness, and irregularities exceeding 2.5 μm are formed on both surfaces at a period of 1000
It is formed randomly over μm.

Next, as shown in FIG. 1 (b), a negative type X-ray resist 2 made of chloromethylated polystyrene manufactured by Toyo Soda Co., Ltd.
It was applied to a thickness of 0.5 μm. Here, since the period of the irregularities on the surface of the Be thin film was larger than the resist film thickness, the resist film thickness was almost uniform.

Subsequently, as shown in FIG. 1 (c), the entire surface of the Be thin film 1 is irradiated with X-rays, and the X-ray resist 2 is exposed to the X-rays transmitted through the Be thin film. The X-ray wavelength used here is 50 °.

Then, through a development process, as shown in FIG. 1D, a resist pattern 3 is formed in a region where the thickness of the Be thin film 1 is small and the amount of X-ray transmission is large. A baking treatment is performed at 210 ° C. for 30 minutes with the thus obtained resist pattern surface horizontal.

Further, the same processing as that performed in FIGS. 1A to 1D is performed again on the back surface of the Be thin film 1, and as shown in FIG. An X-ray window formed by forming a resist pattern on both surfaces of the thin film is obtained.

Using the thus obtained Be thin film as an X-ray extraction window, the entire surface of a PMMA resist applied to a thickness of 1 μm on a silicon substrate was exposed using an X-ray source having a wavelength of 10 °. Then, development was performed to 0.5 μm, which is half of the resist film thickness, and the variation in development speed was measured. At this time, the variation in the resist film thickness remaining on the silicon substrate surface was about ± 0.03 μm.

From these results, it can be seen that extremely uniform exposure can be performed by using the X-ray window formed by the method of the embodiment of the present invention.

Example 2 First, as shown in FIG.
A 25 μm Be thin film 11 is formed. This Be thin film 11 is not uniform in film thickness, and irregularities exceeding 2.5 μm are formed on both surfaces at a period of 1000
It is formed randomly over μm.

Then, as shown in FIG. 2 (b), a negative X-ray resist 12 manufactured by Shipley and designated as SAL-601ER7 was applied to the surface of the Be thin film so as to have a film thickness of 0.75 μm. Also here, since the period of the irregularities on the surface of the Be thin film was larger than the resist film thickness, the resist film thickness was almost uniform.

Subsequently, as shown in FIG. 2 (c), the whole surface of the Be thin film 11 is irradiated with X-rays so as to be perpendicular to the Be thin film. Expose. This X-ray has a wavelength of 100 °.

Then, through a development process, as shown in FIG. 1D, a resist pattern 13 is formed in a region where the thickness of the Be thin film 1 is small and the amount of X-ray transmission is large. Here, the exposure and development processes are performed at the portion where the thickness of the residual resist is largest.
The irradiation amount and the development conditions were adjusted to 0.6 μm. Here, the X-ray irradiation amount in the exposure step is 250 mJ / cm ² ,
Pre-development heat treatment conditions were 150 ° C. for 2 minutes and development time was 90 seconds.

A baking treatment is performed at 210 ° C. for 30 minutes with the thus obtained resist pattern surface horizontal.

Thereafter, as shown in FIG. 2 (e), the Be thin film is placed on a base electrode of a vacuum vessel having parallel plate electrodes, and a sputtering process using Ar gas is performed to expose the Be thin film from the resist pattern 13. The surface of the Be thin film 11 was etched by about 0.6 μm to remove the resist pattern 13. The sputtering conditions at this time were a pressure of 50 mTorr, a power of 150 W, and 2
Etching was performed for 5 minutes.

After this, the back surface of the Be thin film 11 is again
By performing exactly the same processing as performed in FIGS. 2 (a) to 2 (e), an X-ray window having a uniform Be thin film transmittance is obtained as shown in FIG. 1 (f).

Using the thus obtained Be thin film as an X-ray extraction window, the entire surface of a PMMA resist applied to a thickness of 1 μm on a silicon substrate is exposed using X-rays having a wavelength of 10 °, 0.5 μm, which is half of the resist film thickness,
Development was performed, and the variation in development speed was measured. At this time, the variation in the resist film thickness remaining on the silicon substrate surface was about ± 0.02 μm.

From this result, it can be seen that extremely uniform exposure can be performed by using the X-ray window formed by the method of the second embodiment of the present invention.

In the above-described embodiment, the processing is performed once on each side, but the uniformity and mechanical strength are improved even on only one side, and the uniformity is further improved as the number of times is increased.

Further, the X-ray used for exposure at the time of forming the X-ray window is not limited to the one used in the embodiment, but can be appropriately selected. The wavelength of the X-ray does not need to be the same as the wavelength of the X-ray source using the X-ray window, but should be longer than that of the X-ray source to match the photosensitive characteristics of the resist. And an X-ray window with higher uniformity can be obtained.

〔The invention's effect〕

As described above, according to the method of the present invention, X
A negative-type X-ray photosensitizer film is formed on the surface of the X-ray window material film, X-ray exposure is performed from the X-ray window material film side, and development processing is performed. Since the film pattern is provided, the X-rays that pass through the X-ray window material film
Since the photosensitive material film pattern corresponding to the dose is formed, the photosensitive material film pattern is left in a region of the X-ray window where the X-ray transmittance is large, and this functions as an absorber for X-rays. By matching the pattern film thickness and photosensitive characteristics, it is possible to improve the uniformity of transmission of the X-ray window.

[Brief description of the drawings]

FIGS. 1 (a) to 1 (e) are views showing a process of forming an X-ray window according to a first embodiment of the present invention, and FIGS. 2 (a) to 2 (f) are drawings of the present invention. FIG. 9 is a diagram illustrating a process of forming an X-ray window according to a second embodiment. 1 ... Be thin film, 2 ... Negative X-ray resist, 3 ... Resist pattern, 11 ... Be thin film, 12 ... Negative X-ray resist, 13 ... Resist pattern.

Claims (1)

(57) [Claims] A photosensitive agent film forming step of forming a negative type X-ray photosensitive agent film on the surface of the X-ray window material film; an exposure step of performing X-ray exposure from the X-ray window material film side; A developing step of developing the formed latent image, wherein an X-ray photosensitive agent film pattern is selectively left in a region of the X-ray window material film where the X-ray transmittance is large. Manufacturing method of X-ray window.