JPS6030138A - Mask for x-ray exposure - Google Patents

Abstract

PURPOSE:To simplify a manufacturing process for an X-ray mask, to improve durability and to reduce manufacturing cost by using chromium as an X-ray absorption layer material formed on an X-ray transmitting substrate in a pattern shape. CONSTITUTION:An SiN film as an X-ray transmitting substrate 4 is formed on an Si substrate through a CVD method. A chromium film 5 is shaped on the SiN film 4 through an evaporation method, and a desired resist-pattern 6 is formed on the chromium film 5. The chromium film 5 is removed through ethcing while using the resist-pattern 6 as a mask. A reactive ion etching device is employed as a device and CCl4 as a gas at that time. The resist 6 is peeled by oxygen plasma, and the central section of the Si substrate 3 is removed through etching by a KOH solution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an XIII exposure mask used in the manufacturing process of semiconductor devices.

[Prior art]

Recently, for example, in order to form a pattern of around 1 μm,
Line exposure technology is attracting attention. The XI* exposure mask used for this X-ray exposure consists of an X-ray transmitting substrate 2 and an X-ray absorbing layer 1, as shown in FIG. The materials for the TW X-ray transparent group @2 include SiN, SiC,
Inorganic materials such as BN and organic materials such as polyimide are used, and the material for the X-ray absorption layer 1 is generally gold, which has a high absorption coefficient for soft X-rays.

However, because gold is chemically stable, forming a gold pattern that will become this absorbing layer requires dry etching techniques that use reactive gases, such as gas plasma etching and reactive ion etching, which are commonly used in one step of lithography. cannot be applied.

Furthermore, since gold is stable against various chemicals, it is difficult to apply wet etching to it.

For this reason, a lift-off process is generally used to form gold patterns, but this method has problems such as the complexity of the process, making it impossible to form stable patterns, and the tendency to cause pattern defects. This is inappropriate as a pattern forming method.

In addition, the ion milling method is one of the dry etching techniques that irradiates the sample with inert ions such as argon and performs etching only by physical reaction. It is applied to gold patterning because of its high accuracy. However, since the cross section of a sample etched by ion milling tends to be tapered, it is difficult to apply this method to pattern formation of an X-ray mask.

Furthermore, since gold has poor adhesion to the substrate, it is necessary to use a multilayer structure with a material with excellent adhesion, such as tantalum or chromium, sandwiched between the substrate and the mask, which complicates the mask manufacturing process. There is.

Furthermore, since gold has a relatively low hardness, the pattern is easily scratched, which shortens the life of the X-ray mask.

Furthermore, since gold is expensive, the manufacturing cost of the X-ray mask is also high.

[Summary of the invention]

The present invention has been made in view of the problems of the conventional ones as described above, and it simplifies the manufacturing process of X-ray masks by using chromium as the material for the X-ray absorbing layer patterned on the X-ray transparent substrate. ification.

It is an object of the present invention to provide an X-ray exposure mask that can improve durability and reduce manufacturing costs.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows an example of an X-ray exposure mask according to an embodiment of the present invention in the order of manufacturing steps. In the figure, 4 is a SiN film that becomes an X-ray transparent substrate that is irradiated with X-rays for exposure, 5 is a Cr film that is patterned on the SiN film 4 and becomes an X-ray absorption layer, 6 is a resist pattern, and 3 is St It is a board.

Next, the manufacturing process will be explained.

First, a SiN film that will become the X-ray transparent substrate 4 is deposited on the Si substrate 3 using carbon.
It is formed to a thickness of 4 μm by the VD method (ta+ in FIG. 2). Next, a chromium film 5 is formed on the SiN crotch 4 to a thickness of 5000 mm by vapor deposition (Fig. 2(b)), and a desired resist pattern 6 is formed on this chromium film 5 (Fig. 2(C)). . Then, using this resist pattern 6 as a mask, the chromium film 5 is removed by etching. At this time, a reactive ion etching device was used, and CC4 was used as the gas (FIG. 2(d)). Thereafter, the resist 6 is stripped off using oxygen plasma, and the central portion of the Si substrate 3 shown in the figure is further removed with KO.
It was removed by etching with solution I-1 (Fig. 2(e)).

In the X-ray exposure mask according to this embodiment formed as described above, since chromium has a large absorption coefficient for soft X-rays, the chromium film 5 can sufficiently play the role of an absorption layer. Further, since chromium has high reactivity with chlorine-based gases, pattern formation can be performed by commonly used plasma etching or reactive ion etching. Further, since chromium has strong adhesion to the substrate, there is no need to sandwich other materials between the transparent substrate 4 and the chromium film 5. It also has greater hardness than gold, which improves the durability of the mask. Additionally, chromium is less expensive than gold, which reduces manufacturing costs.

Incidentally, in the above embodiment, the number of chromium rays was set at 5,000, but this should be changed depending on the wavelength of the X-rays used.

Further, the substrate materials in the above embodiments are merely examples, and may be other inorganic, organic, or composite films thereof. Also, the chromium pattern may be formed by any other method.

〔Effect of the invention〕

As described above, according to the present invention, XIJ! Since chromium is used as the material for the X-ray absorption layer patterned on the transparent substrate, the manufacturing process for X-ray exposure masks can be simplified, durability improved, and manufacturing costs reduced. There is.

[Brief explanation of the drawings] Fig. 1 is a sectional view showing the structure of a conventional X-ray exposure mask;
FIG. 2 is a sectional view showing an example of a manufacturing process for an X-ray exposure mask according to an embodiment of the present invention. 4...SiN film (X-ray transparent substrate), 5...Cr film (
X-ray absorption layer). Agent Masuo Oiwa

Claims (1)

[Claims] (1) An X-ray transmitting substrate that transmits X-rays for exposure, and
An X-ray exposure mask characterized by comprising an X-ray absorption layer made of chromium and patterned on a radiation-transmissive substrate.