JPS6254919A - Manufacture of x-ray exposing mask - Google Patents

Abstract

PURPOSE:To reduce the strain of a wafer after bonding by releasing excess adhesive between a reinforcing ring and the wafer through a retaining groove, and using a buffer plate. CONSTITUTION:A wafer 3 in which a basic film of an X-ray exposing mask is accumulated through an adhesive 2 is placed on the bonding surface 11a of a reinforcing ring 11 in which an adhesive retaining groove 12 and a through hole 13 communicating with the groove 12 of the surface 11a are formed, a retainer 15 is superposed through a buffer plate 14 made of a material softer than the wafer 3 thereon, the adhesive 2 is solidified in the state pressed from outside in a superposing direction to bond the wafer 3 to the ring 11. Thus, even if a vice 6 is used, its end is not contacted with the wafer 3, and since the excess adhesive 2 between the ring 11 and the wafer 3 can be released through the groove 12 to the hole 13, the wafer 3 is contacted uniformly with the entire surface of the ring 11 together by the draping action of a buffer plate 14 having flexibility.

Description

[Detailed Description of the Invention] [Summary] When bonding a wafer on which a mask base film is to be deposited to a reinforcing ring during the manufacture of an X-ray exposure mask, a reservoir groove having an adhesive escape hole is provided in the reinforcing ring, By adding a presser plate when pressurizing the wafer placed on the reinforcing ring with adhesive interposed, the distortion of the wafer after bonding is reduced and the flatness of the base film is improved. be.

[Industrial application field]

The present invention relates to a method for manufacturing an X-ray exposure mask, and in particular,
The present invention relates to a method of bonding a wafer on which a mask base film is deposited to a reinforcing ring.

In the manufacture of semiconductor devices, photolithography technology is used to perform microfabrication on semiconductor substrates. In the step of exposing a pattern in this technique, from the viewpoint of mass production, a method is often used in which the pattern is transferred all at once, and a mask is used in which the pattern is formed due to the difference in light transmittance and becomes the transfer light.

In addition, ultraviolet rays have conventionally been used as the light used for the above-mentioned transfer exposure, but as patterns become finer due to the integration of Mi in semiconductor devices, the diffraction phenomenon of light has become a problem. However, the use of X-rays with even shorter wavelengths is also being considered.

Due to the characteristics of X-rays, the mask used for X-ray exposure has a 5-μm-thick crotch made of boron nitride (BN) or silicon nitride (Si3N4) as a transparent substrate, and a ridge on the base film. As the light shielding film to be patterned, a film made of, for example, gold (^U) and having a thickness of about 1 μm is used.

In the X1* exposure, as shown in the schematic side view of FIG. 2 showing the main part, the irradiated X iQ L is radiation light from the point light source LS, so the path of the X-rays is the same as the exposed substrate. In the portion inclined with respect to S, the variation d in the distance between the substrate S and the mask M causes distortion of the exposure pattern.

For this reason, it is desirable that the base film of the X exposure mask be formed flat despite its thinness.

[Prior art] For example, an X-ray exposure mask is shown in a cross-sectional side view of the process in FIG. 3 (
It is manufactured by the procedures shown in a) to (C).

That is, first of all, as shown in FIG.
A silicon wafer 3 for a semiconductor device is bonded to the bonding surface 1a using an adhesive 2 such as epoxy (eg, Araldite).

Next [see Figure (b)], BN or 513N4 with a thickness of about 5 μm, which will become the base film 4 of the mask, is deposited on the wafer 3-H by chemical vapor deposition (CVD).

Next, as shown in FIG. 01, the inner region of the reinforcing ring l of the wafer 3 is removed by etching to form a base film 4, and a patterned light-shielding film 5 made of Au or the like with a thickness of about 1 μm is formed on the base film 4. is formed to complete an X-ray exposure mask.

Here, the outer diameter of the reinforcing ring l is about 100 to 150 tmψ in accordance with the outer diameter of the wafer 3, the ring width is about 20n, the thickness is about 5mm, and the thickness of the wafer 3 is 0.
It is about 6**.

Note that when this mask is used for the exposure shown in FIG. 2, the top and bottom of FIG. 3 are reversed.

The bonding method described in FIG. 3(a) in the above process is as shown in the partial side sectional view of FIG.

That is, the adhesive 2 is applied to the bonding surface 1a-1 of the reinforcing ring 1, and the wafer 3 is placed on the reinforcing ring 1, and the reinforcing ring 1 is divided into a plurality of parts, for example, into four parts, and each part is placed approximately in the center of the ring width at each dividing position. The wafer 3 is fixed to the reinforcing ring 1 by clamping the wafer 3 under pressure from above and below with a vise 6, and in this state, the adhesive 2 is heated and solidified.

[Problem that the invention seeks to solve]

According to the above bonding method, even though the bonding surface la of the reinforcing ring l is flat, the wafer 3 is not necessarily flat, and for example, the wafer 3 is bonded in an uneven and distorted state as shown in FIG. Ru.

According to the experience of the inventor of the present application, the above distortion is approximately 5 μm in terms of the flatness of the wafer 3. And this distortion is the third
The above 5 μm is a problematic value because it is inherited by the flatness of the base film 4 explained in the figure and leads to the variation d explained in FIG. 2.

It is thought that the above distortion occurs because the tip of the vise 6 directly touches the wafer 3, and stress is applied to the wafer 3 due to its rotational force.

[Means for solving the problem] Fig. 1 is a partial side sectional view showing an embodiment of the method of the present invention.
and a partial plan view of the reinforcing ring (bl).

The above problem is that, as shown in FIG. 1, the adhesive 2
A wafer 3 on which a base film of an X-ray exposure mask is to be deposited is placed on top of the wafer 3 with a buffer plate 14 made of a material softer than the wafer 3 interposed therebetween, and a holding plate 15 is stacked on top of the wafer 3. This problem is solved by the manufacturing method of the present invention, in which the wafer 3 is bonded to the reinforcing ring 11 by solidifying the adhesive 2 under pressure.

[Effect]

Bookffl! According to this method, even if the vise 6 is used for the above-mentioned pressurization as in the conventional method example shown in FIG. Since the excess adhesive 2 can escape into the through hole 13 through the reservoir groove 12, the wafer 3 is evenly spread over the entire surface of the reinforcing ring 11 due to the adapting action of the flexible buffer plate 14. come into contact with

In this way, the strain on the wafer 3 bonded to the reinforcing ring 11 is significantly reduced compared to the case of the conventional method, and accordingly
The flatness of the base film 4 explained in the figure is improved, the variation d explained in FIG. 2 is reduced, and pattern distortion during exposure is improved.

〔Example〕

An example of wafer bonding by the method of the present invention will be described below with reference to FIG.

The reinforcing ring 11 used has the same material and external dimensions as the reinforcing ring 1 used in the conventional method example. On the bonding surface 11a to which the wafer 3 is bonded, there are three adhesive reservoir grooves 12, which are concentric with the outer shape and have a width of about 3 squares and a depth of about 0.1 square, and are distributed approximately evenly with respect to the ring width. Furthermore, a diameter of approximately 211φ is provided at each position that divides the longitudinal direction of each reservoir groove 12 into approximately six equal parts, and serves as an escape hole for the adhesive in the thickness direction.
A through hole 13 is bored.

Also, there is a buffer plate 14 which is made of a Teflon plate with a thickness of about 3 fl and has an outer diameter that matches the outer diameter of the reinforcing ring 11, and a buffer plate 14 which is made of an alumina plate with a thickness of about 7 fl and whose outer diameter is the same as the buffer plate 14. A pressing plate 15 in the form of a disc is prepared in advance.

The wafer 3 is bonded by applying the adhesive 2 on the bonding surface 11a of the reinforcing ring 11, placing the wafer 3 thereon, and then stacking the buffer plate 14 and the holding plate 15 in that order. Similarly, the ring of the reinforcing ring 11 is divided into a plurality of parts, for example, into four parts, and the approximately central part of the ring width at each divided position is held under pressure from above and below with a vise 6 to fix the wafer 3 to the reinforcing ring 11. In this state, the adhesive 2 is heated and solidified.

In this way, as described above, the wafer 3 is bonded in uniform contact with the entire surface of the reinforcing ring 11, and the distortion of the wafer 3 after bonding becomes 1,17111 or less in terms of flatness.

The above-mentioned distortion is 115 or less in the conventional method example, and reduction of this distortion greatly contributes to improvement of pattern distortion during exposure.

〔Effect of the invention〕

As described above, according to the configuration of the present invention, when a wafer on which a mask base film is deposited is bonded to a reinforcing ring during the manufacture of an X-ray exposure mask, distortion of the wafer after bonding can be reduced. This has the effect of improving the flatness of the base film, thereby making it possible to improve pattern distortion during exposure.

[Brief explanation of drawings]

FIG. 1 is a partial side sectional view (al
and a partial plan view fbl of the reinforcing ring, FIG. 2 is a schematic side view showing the main parts for X-ray exposure, and FIG. FIG. 4 is a partial side sectional view showing an example of a conventional method for bonding wafers, and FIG. 5 is a diagram illustrating problems with the conventional method. In the figure, 1 and 11 are reinforcing rings, la and 11a are adhesive surfaces, 2 is adhesive, 3 is wafer, 4 is base film, 5 is light shielding film, 6 is vise, 12 is adhesive reservoir groove, 13 is 14 is a buffer plate, 15 is a presser slope, L is an X-ray, LS is a light source of L, M is a mask, S is a substrate to be exposed, and d is a variation.

Claims (1)

[Claims] Adhesive ( A wafer (3) on which a base film of an X-ray exposure mask is to be deposited is placed with the wafer (2) interposed therebetween, and a buffer plate (14) made of a material softer than the wafer (3) is interposed thereon to form a holding plate. (
An X-ray exposure mask characterized in that the wafer (3) is bonded to the reinforcing ring (11) by stacking the wafers (15) and solidifying the adhesive (2) while applying pressure from the outside in the stacking direction. manufacturing method.