JPS61245161A - Manufacture of x-ray mask - Google Patents

Abstract

PURPOSE:To enable a fine X-ray absorbing pattern to be formed with high precision by using a material transmitting X-rays for a mask layer to be used form selective electroplating and leaving the mask layer without removing it. CONSTITUTION:A BN film 12, an Au film 13, the first polyimide film 14, an SiO2 film 15 and a resist film 16 are formed on a silicon wafer 11 and it is exposed and developed to form a resist pattern and further, etched to form an SiO2 pattern. Then, the first polyimide film 14 is patterned with this pattern to form a pattern 14a and an Au film 17 is formed in the gaps in this pattern 14a, the film 15 is removed, leaving the film 14 as it is, and the second polyimide film 18 is formed, thus permitting the first polyimide film 14 to be left as it is after the formation of the Au film 17, accordingly, the film 17 to be hardly broken, and fine X-ray absorbing pattern to be formed with high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A fine X-ray absorption pattern can be formed in the manufacture of an X-ray mask in which an X-ray absorption pattern is provided on an X-ray transmission film.

[Conventional technology]

For example, a photoresist film (hereinafter referred to as a resist film) is formed on a silicon wafer, exposed and developed to create a resist pattern, and processes such as etching are often performed using this resist pattern as a mask. The mask used to expose such a resist film is a pattern of, for example, chromium (Cr) formed on a glass substrate, and the resist film is exposed by irradiating ultraviolet light (UV light) through the mask on the glass substrate.

Recently, there has been a demand for the creation of fine patterns to increase the degree of integration of integrated circuits, but when using conventional ultraviolet light, there are limits to pattern width and pattern spacing.
Exposure using X-rays is being researched, taking advantage of the fact that light with short wavelengths is less likely to be diffracted.

A conventional X-ray mask is made, for example, by the following first method.

First, as shown in FIG.
1, a boron nitride (BN) film 32 and a gold (Au) film 33, which will serve as a mask support, are formed in this order. Next, the back side of the silicon wafer is etched leaving the peripheral portion 31a. Subsequently, a resist film 34 is applied and formed on the Au film 33.

Next, as shown in FIG. 2(b), exposure and development steps are performed to form a resist pattern 34a.

Next, as shown in FIG. 2 (C1), the Au film 33 is connected to the electrode and plated with Au, and the resist pattern 34 is
The space between a is filled with an Au layer 35.

Next, the resist pattern 34a is peeled off to expose the Au film 33 (FIG. 2(d)).

Next, as shown in FIG. 2(e), the exposed portions of the Au film 33 are removed by slicing.

Finally, as shown in FIG. 2 (1), a polyimide film 36 is coated on the surface of the already formed film.

A second conventional method of making an X-ray mask is shown in FIG.

First, as shown in FIG.
1, a BN film 32. The Au film 33 is formed in order, and the Au film 33 is formed in order.
Tantalum (Ta) 1ff37 is formed on the film 33,
A resist film is applied and formed thereon for 3 days.

Next, as shown in FIG. 3(b), the resist is exposed to light.
Developed to form a resist pattern 38a, CC1, 4
The exposed portion of the Ta film 37 is removed by etching to partially expose the underlying Au film 33.

Next, sputter etching using Ar was performed as shown in FIG. 3(0).
The exposed ^U film 33 is removed as shown in Figure 2, and finally polyimide is coated in the same manner as in the first method.

[Problem that the invention seeks to solve]

For example, in the first conventional method described above, the thickness is 0.7 μm,
If you try to form a fine submicron pattern with 1tlio or 5μ steel, it may be damaged in the resist stripping process explained with reference to Figure 2(e), and Au is originally a weak (soft) material. Therefore, there is a problem that the Au pattern collapses or comes off.

In the second conventional method, the Au pattern is formed by sputter etching using Ar;
Because etching is performed by physical impact, the Au pattern formed is tapered or obliquely etched, making it difficult to miniaturize the formed Au pattern and causing problems in accuracy. .

The present invention was created in view of these points, and an object of the present invention is to provide a method for forming fine X-ray absorption patterns without damaging them in the production of X-ray masks.

[Means for solving problems]

FIGS. 1A to 1J are cross-sectional views of an X-ray mask in the process of carrying out the method of the present invention.

In FIG. 1, a BN film or silicon nitride film 12, an Au film 13, a first polyimide film 14, and silicon dioxide (5i02) are formed on a silicon wafer 11. 15, to form the resist film 16 (Fig. 1(d)), Fig. 1(hl
As shown in FIG. 3, a resist pattern 16a is formed by performing exposure and development steps, and the 5iOz film is patterned by reactive ion etching using carbon dioxide to form a 5i02 pattern 15a. Further 5i02 pattern 15
Using a as a mask, the first polyimide film 14 is patterned by oxygen paste active ion etching (RIB), and the Au film 17 is attached to the gap, and the 5i02 film 15 is removed while leaving the pattern of the first polyimide film 16 as it is. A second polyimide film 17 is formed over the entire surface.

[Effect]

After the Au film 17 that becomes the X-ray absorption pattern is attached between the first polyimide patterns, the first polyimide patterns are left as they are, so damage to the Au film 17 is prevented and the first polyimide patterns are The neuimide film is etched by RIB, and its pattern is formed finely and with high precision, so the second Au film pattern buried between the patterns is also formed finely and precisely.

[Embodiment 1] Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. 1 again.

FIG. 1(a): On a silicon wafer 11 with a thickness of 500 to 600 μm,
BNNiP3, which will serve as a mask support, is formed by growing BN to a thickness of 3 to 5 μm using a reduced pressure vapor deposition (CVD) method.

FIG. 1(b): Au is deposited to form a mask layer of Au1ii13 having a thickness of 100 mm. This Au film is formed to be used as a coating base when plating the Au layer in a later step, but if the Au film 13 is thin enough, it will transmit X-rays and will not interfere with the X-ray mask.

FIG. 1(C): Polyimide is coated to a thickness of 1.0 to 1.5 μm and cured to form a first polyimide film 14. FIG.

To cure, heat at 80°C, 200°C, and 300°C for 30 minutes each (the temperature is 100°C, 200°C).
C, 300°C). Next, the central portion of the back surface of the silicon wafer is etched, leaving a peripheral portion 11a. Therefore, it becomes a BNNiP3 mask support.

Figure 1(d): 5i02 film 15 is coated or sputtered with SiO+ (or metal material) to a thickness of 3000 nm.
A resist film 16 is formed by coating a resist, for example, a resist with a trade name of 0FPR800, to a thickness of 0.5 to 1.5 μm.

FIG. 1(e) Using a resist pattern obtained by exposing and developing the Ni resist as a mask, the SiO+ film 15 and the first polyimide film 14 are etched by RIB to form a pattern 14a. This RIB was performed using CFI gas in the same chamber.
Polyimide is continuously etched using i02 and oxygen (02) gas.

Figure 1(f): 0.7% Au is applied to the grooves between the patterns 14a by electrolytic plating.
Add it to a thickness of μ- to form ^um17. In this plating, the Au layer 13 is connected to the electrode. The thickness of the Au layer 17 is set to be slightly smaller than the thickness of the pattern 14a including the first polyimide and 5iOs+.

Figure 1 (g): SiO2 was removed by plasma etching using CF and gas, and the entire surface was coated with polyimide to a thickness of 2.0 to 4.0 μm, and etched at temperatures of 80°C, 200°C, and 300°C, respectively. When the second polyimide film 18 is formed by heating and curing for 30 minutes, an X-ray mask is completed.

In the above steps, the Au layer 17 is formed in the groove between the polyimide and SiO2 patterns 14a, and the pattern 14
Since the second polyimide film is formed while a is left as is, the pattern of the Au layer 17 is not damaged.
One of the old problems has been solved.

Further, when forming the pattern 14a, since the RIB etches with good directionality, the pattern accuracy does not deteriorate as in the conventional example.

[Example 2] In the second example of the present invention, BNNi was deposited on the silicon wafer 11 as in FIG. 1(a).
P3 mold. Indium oxide 95 as shown in Figure 1 (1)
A mixed film (CITO film) 19 containing 5% tin oxide and 5% tin oxide was formed by sputtering. The Au film 13 is formed by vapor deposition to a thickness of 10 to 20 layers. By applying the polyimide coating and subsequent steps in the same manner as in Example 1, an X-ray mask as shown in FIG. 1(j) is completed.

In the case of Example 2, since the ITO film is a transparent conductive film, A
Electrolytic plating is possible even if the u film 13 is made as thin as 10 to 20 layers. Furthermore, since the Au is made thinner, light can pass through the region of the mask where there is no X-ray absorber, making it possible to align the mask using light.

〔Effect of the invention〕

As described above, according to the present invention, in manufacturing an X-ray mask, a fine X-ray absorption pattern can be formed accurately without being damaged.

[Brief explanation of drawings]

FIG. 1(a) or a is a sectional view of the first embodiment of the present invention;
FIG. 1 (hl to 0) is a sectional view of the second embodiment of the present invention;
Figure 2 (al or phantom is a sectional view of an X-ray mask (conventional example) in the first conventional method step, and Figure 3 (al or C1 is a cross-sectional view of an X-ray mask (conventional example) in the conventional second method step) (Conventional Example) In Fig. 1, 11 is a silicon wafer, 11a is a peripheral portion of the silicon wafer, 12 is a BN film, 13 is an Au film, 14 is a first polyimide film, 14a is a pattern, 15 is a SiO2 film, 16 is a resist film, □ 17 is an Au layer, 18 is a second polyimide film, and 19 is an ITO film. Gambling History Example Vinegar Figure 1 tt#'l#, li li 1ken (East#'l#1fil! II No. 211!!!

Claims (2)

[Claims] (1) An X-ray mask is formed by selectively electrolytically plating an X-ray absorber on a thin film (12) that transmits X-rays using a mask layer (13) from which selected areas are removed. A method for manufacturing an X-ray mask, characterized in that the mask layer (13) used in selective electrolytic plating is made of a substance that transmits X-rays, thereby leaving the mask layer as it is without removing it. (2) Forming a transparent conductive thin film on a thin film that transmits X-rays,
2. The method of claim 1, further comprising the step of forming a mask layer for electrolytic plating.