JPH01289114A - Process and device of x-ray exposure - Google Patents

Abstract

PURPOSE:To facilitate the manufacture of an exposure mask by a method wherein specified soft X-rays are led in pressure-reduced He atmosphere through the intermediary of a diamond carbon type film to transfer a pattern of an X-ray exposure mask using the carbon film as a substrate. CONSTITUTION:A beam line 12 is connected in the tangential line direction of an electron track of an electron storage ring 11 in wave length exceeding 44Angstrom to pressure-reduce the inside of the beam line 12. The soft X-rays 13 radiated from the storage ring 11 are taken in the beam line 12 to be totally reflected by a mirror 14. The intermediate part of the beam line 12 is sealed with a diamond type carbon film 15 to lead the gas into a specimen chamber 16 between the carbon film 15 and the terminal of the beam line 12. A wafer 18 coated with an X-ray resist is overlapped with the diamond type carbon film 15 using X-ray exposure mask 17 formed of a pattern and then an exposure shutter 19 is opened to irradiate the wafer 18 with the totally reflected soft X-rays by the mirror 14 for the transfer of said pattern. Through these procedures, the X-ray exposure mask can be manufactured easily.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an X-ray exposure method for the purpose of highly accurate transfer of fine patterns, and an SR exposure apparatus using synchrotron orbital synchrotron radiation as a pattern transfer medium.

(Prior art) In a conventional SR exposure system, an electronic storage ring whose synchrotron radiation intensity peaks at several to 10 m is used as a light source, and the synchrotron radiation is extracted into a vacuum beam line and is deposited into a film with a thickness of several tens of liters and one meter. In a He atmosphere separated from the beam line using Be foil, pattern transfer is performed using an X-ray exposure mask with a thin film such as SiNx, SiC, or Si as a substrate (for example, North Holland Publishing Co., Ltd. North-Holland P
Nuclear Instruments and Methods published by Publishing Company.
Instruments and Methods) Vol. 208 (page 1983), p. 281).

(Problem to be solved by the invention) Not only the conventional SR exposure apparatus described above but also the conventional plasma
Exposure equipment that uses radiation sources or electron beam excitation
The line absorber pattern had to be formed of a heavy metal with a film thickness of approximately lpm, and it was essential to form a mask pattern with a large aspect ratio. However,
It is very difficult to form an X-ray absorber pattern with a large aspect ratio and to repair defects, and not only has it been impossible to form a desired X-ray absorber pattern, but it has also been difficult to form an X-ray absorber pattern with a large aspect ratio.
Since an X-ray absorber pattern with a film thickness of 1 μm is formed on a mask substrate with a thickness of 2 pm to 2 pm, the distortion of the mask due to the stress of the X-ray absorber pattern increases, making it difficult to align the pattern according to the dimensions of the transferred pattern. It was extremely difficult to ensure accuracy.

The present invention aims to reduce the difficulty of manufacturing an X-ray exposure mask, which is the biggest drawback of X-ray exposure technology, and to improve the accuracy. An object of the present invention is to provide an X-ray exposure method that can obtain sufficient contrast with an absorber pattern, and an X-ray exposure apparatus used therein.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention uses soft X-rays with a longer wavelength than conventional ones for exposure, and uses diamond-like carbon fibers that have a high transmittance to soft X-rays of 4 Å or more. Pattern transfer is performed using an X-ray exposure mask in which a heavy metal pattern with a film thickness of 0.1 pm to 0.2 pm is formed on the film substrate. In order to prevent the temperature of the X-ray exposure mask from rising, the X-ray exposure mask is placed in a reduced pressure He atmosphere. Electronic storage
A diamond-like carbon film is used as an isolation window to prevent He gas from entering the vacuum on the ring side.

(Function) In the configuration of the present invention, most of the soft X-rays with a wavelength of 20 Å or more and 44 Å or less are absorbed by the diamond-like carbon mask substrate.
It is done by a line. Except for carbon, which has an absorption edge of 44 mm and a high transmittance in the wavelength range beyond that,
In the wavelength region of 20 Å or more, absorption of all elements is large. Therefore, for example, when Au is used as an X-ray exposure mask pattern material, the required pattern thickness to obtain the contrast value of 20 required for the X-ray mask is: Conventional X-ray exposure by 7 or 8 people is approximately 0.711m or 0.9p.
m, whereas the incidence is only 0.1 pm, making it much easier to manufacture an X-ray exposure mask and correct pattern defects. Furthermore, since the absorption efficiency of the resist increases dramatically, the exposure time is significantly shortened.

(Example) Examples of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a beam line 12 is connected in the tangential direction of the electron orbit of an electron storage ring 11 with a critical wavelength of synchrotron radiation of 20 to 80 people, and the inside of the beam line 12 is vacuum-exhausted. at least 1O using
Reduce the pressure to -5 Pa or less. Soft X-rays 13 emitted from the electronic storage ring 11 are extracted into the beam line 12 and totally reflected by a mirror 14 installed in the vacuum of this beam line.

The middle of the beam line 12 is sealed with a diamond-like carbon film 15 having a thickness of about 1 pm, and the sample chamber 1 between this diamond-like carbon film 15 and the end of the beam line 12 is sealed.
He gas is introduced into 6, and the He pressure is controlled to be 100 Pa to 1000 Pa using a pressure control device. An X-ray surface exposure mask 17 in which a pattern of heavy metal such as Au or W with a thickness of approximately 0.111 m to 0.2 pm is formed on a diamond-like carbon film substrate with a thickness of approximately 1 pm is
The sample chamber 1 is overlaid by any method on a wafer 18 coated with a line resist such as FBM (trade name) or CPMS.
6, the exposure shutter 19 is opened for a predetermined period of time, and soft X-rays totally reflected from the mirror are irradiated to transfer the pattern onto the wafer.

FIGS. 2(a) to 2(e) show an example of a manufacturing process for a diamond-like carbon film. On one surface of the Si wafer 21 having a thickness of several hundred pm to several mm, an etching mask pattern 22 is formed using, for example, an LPCVDS3N4 film for etching a predetermined region of the Si wafer. Figure (a)). After depositing a diamond-like carbon film 23 with a thickness of several hundred nm to lpm on the other surface of the Si wafer 21 by DC glow discharge using CH4 and H2 as reaction gases, the inside of the diamond-like carbon film 23 is deposited. Stress is approximately 2×108 dyn
/cm2 to I
Anneal for one to two hours. Subsequently, by a method such as a sputtering method or an electron beam evaporation method, about 0.
A 1 pm thick heavy metal thin film 24 of any one of W, Au or Ta is deposited on the surface of the diamond-like carbon film 23, and a desired pattern is deposited on this heavy metal thin film 24 using an electron beam exposure technique or a focused ion beam exposure technique. A resist pattern 25 is formed (FIG. 2(C)). Then, using the resist pattern 25 as a mask, the heavy metal thin film 24 is patterned by a method such as reactive ion etching or ion milling (see FIG. 2(d)).
)). Finally, while protecting the heavy metal pattern 24 using an arbitrary jig, S
By etching a predetermined region of the Si substrate 21 using the i3N4 film pattern 22 as a mask, a desired X-ray mask can be obtained. (FIG. 2(e)) If the process of forming an X-ray absorber pattern is omitted in the manufacturing process of this X-ray mask, an X-ray extraction window using a diamond-like carbon film can be obtained.

In the present invention, since the film thickness of the X-ray absorber pattern of the X-ray mask only needs to be 0.1 pm, it is possible to form the pattern by reactive ion etching or ion milling using a resist as a mask, and it is possible to form the pattern by reactive ion etching or ion milling using a resist as a mask. A complicated pattern formation process using multilayer resist technology, such as the X-ray absorber pattern of the mask, is no longer necessary. In addition, defect correction in X-ray absorber patterns, which was almost impossible in the past, can be done without damaging the mask substrate using focused ion beam lithography technology, dramatically increasing the yield of X-ray exposure masks. I was able to improve it.

(Effects of the Invention) As explained above, the present invention uses soft X-rays with long wavelengths longer than the requisite Å as a pattern transfer medium, so the X-ray absorber pattern is about 0.111 m to 0.211 m, which is about the same as the conventional one. 1
Sufficient contrast can be obtained with a thickness of 15 to 1110 mm. Therefore, not only the production of X-ray exposure masks has become much easier, but also the inspection and correction of pattern defects has become much easier. Furthermore, since the distortion of the mask due to the internal stress of the X-ray absorber pattern was reduced in proportion to the decrease in the thickness of the X-ray absorber pattern, the accuracy of mask positioning during X-ray exposure was also dramatically improved. Furthermore, the absorption efficiency of soft X-rays by the resist is increased approximately 50 times, and the exposure time is approximately 11 times longer.
It was shortened to 10 or less.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram showing an embodiment of the X-ray exposure apparatus of the present invention, and FIGS. 2(a) to (e) are schematic sectional views showing the manufacturing process of an X-ray exposure mask. 11...Electronic storage ring, 12...
・Beam line, 13...Mirror, 14...
...Diamond-like carbon film window, 15...Sample chamber, 16...X-ray exposure mask, 17...Wafer, 18...Exposure shutter, 21... S
i wafer, 22...Si3N4.23...
Diamond-like carbon film, 24...heavy metal thin film, 25...resist pattern.

Claims (1)

[Claims] 1. Soft X-rays with a wavelength of 44 Å or more are introduced into a reduced pressure He atmosphere through a diamond-like carbon film, and a pattern formed on an X-ray exposure mask with a diamond-like carbon film as a substrate is exposed on the substrate surface. X-ray exposure method for transferring images. 2. Electronic storage ring and this electronic storage ring.
A beam line that takes out soft X-rays in the tangential direction of the electron orbit of the ring, a mirror installed between the beam lines to totally reflect the soft X-rays, and an aligner that aligns the X-ray exposure mask with the substrate. An X-ray exposure apparatus comprising: a critical wavelength of light emitted from the electronic storage ring is 20 Å or more and 80 Å or less, and a wavelength of soft X-rays totally reflected by the mirror is 20 Å or more. X-ray exposure equipment.