JPH0421852A - Manufacturing of x-ray taking out window - Google Patents

Abstract

PURPOSE:To improve the uniformity of X-ray transmissivity by applying a negative type photosensitive film on one surface of a Be film of an X-ray taking out window and irradiating the film with X-rays from the opposite side, then developing the film. CONSTITUTION:The negative type photosensitive film 4 is formed by applying a negative resist 4 on one surface of the beryllium Be film 3 and hereafter, the film 4 is irradiated with the X-rays 5 from the opposite side. The negative type photosensitive film 4 hardly remains in the position where the Be film 3 is thick and the negative type photosensitive film 4 conversely remains thick in the position where the Be film 3 is thin if such film is developed. Consequently, the total thickness of the Be film 3 and the negative type photosensitive film 4 is uniformized overall and, therefore, the intensity at which the X-rays are transmitted is eventually averaged. The excellent characteristic to uniformize the X-ray transmissivity is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing an X-ray extraction window and an X-ray exposure apparatus using the X-ray extraction window manufactured by the manufacturing method. In particular, the present invention relates to an X-ray extraction window that corrects non-uniformity in thickness, scratches, etc. of the Be window, which is an X-ray extraction window, and improves non-uniformity in X-ray transmittance.

(Prior art and its problems) In recent years, LS1. With the miniaturization of large-capacity integrated circuits such as VLSIs, X-ray exposure using synchrotron radiation (hereinafter referred to as SR) has attracted attention.

In a conventional exposure apparatus of this type, as shown in FIG. 6, X-rays emitted from an acceleration ring 1 are reflected by a mirror 12 and guided to an exposure chamber 13. The atmosphere in the exposure chamber 13 is helium (He) or air, while the atmosphere in the mirror 12 and acceleration ring 11 is ultra-high vacuum.
A vacuum partition 14 is provided between the mirror 12 and the mirror 12 .

As this vacuum partition, an X-ray extraction window made of beryllium (Be), which has high X-ray transmittance and high mechanical strength, is used.

However, the Be window has irregularities on its surface, causing unevenness in the intensity of the transmitted X-rays, resulting in the problem that the irregularities are transferred onto the resist.

Regarding this uneven shape, it was reported in the Japan Society of Applied Physics 4a-6 in the spring of 1989 that it was about 5 μm for rolled films and 2 μm for vapor deposited films. In addition, as a method of removing this strength unevenness, a method of vibrating the Be window is described in 4a.
It has been proposed in -7.

However, this method of vibrating the Be window has the problem that the X-ray exposure apparatus becomes mechanically complex.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an X-ray extraction window with excellent characteristics that makes X-ray transmittance uniform, and an X-ray exposure apparatus having the X-ray extraction window.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention is an X-ray extraction device characterized by including a uniformizing step of applying a photosensitive film to one side of the X$J1 extraction window, irradiating it with exposure light from the opposite side of the applied surface, and then developing it. A method for manufacturing a window and an X-ray exposure apparatus having the X-ray extraction window.

(Function) According to the present invention, a negative photosensitive film is formed on one side of the X-ray extraction window, and by irradiating the film with exposure light from the opposite side and developing it, the X-ray extraction window can be removed. Uniformity of X-ray transmittance is achieved, and as a result, the unevenness on the surface of the Be window, which is the X-cotton extraction window, is not transferred onto the resist.

(Example) Next, the present invention will be described in further detail with reference to examples shown in the drawings.

FIG. 1 is a diagram showing the manufacturing process of an X-ray extraction window according to a first embodiment of the present invention, and FIG. 3 is a diagram showing a part of the X-ray extraction window in FIG. 1. .

As shown in FIG. 1, a negative photosensitive film 4 is formed by coating a negative resist 4 on one side of the Be film 3, and then X-rays 5 are irradiated from the opposite side of the film 4. At this time, the amount of X-ray irradiation is set to an appropriate amount, for example, the amount of irradiation at the position of the thickest Be film 3 is set to the amount at which the negative photosensitive film begins to remain. Set it so that it roars.

When this is then developed, almost no negative photosensitive film 5 remains at the thicker positions of the Be film 3, whereas a thicker negative photosensitive film 4 remains at the thinner Be film 3 positions. Since the total thickness of the film 3 and the negative photosensitive coating 4 is uniform throughout, the intensity of X-ray transmission is made uniform.

Next, the above phenomenon will be explained in more detail with reference to FIGS. 2 and 3.

Figure 2 is negative resist (chloromethylated polystyrene)
The vertical axis shows the normalized residual film rate T, and the horizontal axis shows the amount of X-ray irradiation. The irradiation amount is negative photosensitive coating 4
The amount of radiation that begins to remain.

is standardized as 1.

This characteristic curve is determined by the irradiance. T=-y within the range of ~2Do
It can be well approximated by the formula expressed as log D=1, 61log D (2).

Figure 3 shows the shape of the resist 4 coated on the surface of the Be film 3, where IA is the X-ray intensity that has passed through the top point A on the thickest Be film in the X-ray transmission area, and Let the point be B, and the intensity of the X-rays transmitted through this point be 18. In such a system, the irradiation amount at point A is high. When irradiated with X-rays, the remaining film rates at points A and B become O1 and 0.0, respectively.
4, and if a 2 μm negative resist is applied as the initial film thickness, a 0.8 μm negative photosensitive film 4 is applied at point B.
will remain. As a result, when comparing the X-ray transmittance of the original Be film 3, the transmittance at point A remains unchanged and the transmittance decreases only at point B, which alleviates the non-uniformity of the X-ray transmittance. .

The uniformity of this X-ray transmittance is shown below when calculated under the conditions that, for example, 10 people were irradiated with X-rays and a negative resist (chloromethylated polystyrene) was applied to a thickness of 2 μm.

First, the X-ray intensity was transmitted through Bc43 with a thickness of tμm. (
t,) is ■o(t)=■o(0)exp(-μB,,-1)
■The results are shown in Figure 4. It was shown in Here, μIle is the linear absorption coefficient of the Be film.

When irradiated with X-rays, the negative resist coated on the back side becomes Be
This X-ray intensity that has passed through the membrane 3 is ■. (1,). X transmitted through the thickest Be film 3 (thickness)
Increased radiation dose. If the amount of X-ray irradiation is set in advance so that the amount of irradiation transmitted through the Be film 3 of thickness t is
From the equation (2), the thickness of the negative photosensitive film remaining after development T Rh) is TJt), where T is the applied film thickness.
0.434γ・T + jln-・(to-t) ■
It can be expressed as

Transmittance I, (t) of the X-ray extraction window created in this way
is I + (t
l= I o(t)' exp(-u R-TR(t
)) (2) If this is standardized by I, (10) (transmittance at a position of 10 μm on the mask substrate), the result will be as shown in FIG.

As a result, ■ in Figure 4. If you compare L with
It is clear that the line intensity has been made uniform.

However, as shown in FIG. 4, there is still unevenness in the transmitted X-ray intensity by ±10% or more. Therefore, by repeating the homogenization process again on the X-ray extraction window created by the above-described homogenization process, the transmitted X-ray intensity can be made even more uniform. Therefore, by repeating this multiple times, the X-ray intensity can be made uniform to a desired value.

For example, when it is desired to obtain an X-ray extraction window with a uniformity of X-ray transmission intensity of ±2%, the average thickness of the Be film 3 is tv, and the minimum film thickness is jm+. The number n of repetitions of the equalization process may be determined so that

Here ■. (1) is the X-ray transmission intensity at the same position after repeating the homogenization process n times for a t μm thick Be film,
It can be expressed by the following formula.

1, (t) = I oexp(-μBe・t)exp[1l-(1-k
)') μga△L]■Here, △t and k are Δ1=1.1, assuming that the maximum Be film thickness is t. -1, k=0.434・γ・T, μ3. Therefore, if we calculate the number of repetitions n from equation 0, we get:

Here, on the Be window with a film thickness to = 10 ± 3 μm, γ1.6
Considering the case where a negative resist of 2 μm (=TI) is applied, n=9 can be derived from equation 0.

This is shown as I9 in FIG. Be film thickness] 0±3
It can be seen that the transmitted X-ray intensity is within ±2% in the μm range, and that the transmitted X-rays are made uniform.

In addition, in the method for producing an X-ray extraction window of the present invention, the surface to which the resist is applied in the uniformization process does not need to be coated on the same surface when the uniformization process is repeated multiple times, but can be applied in each process. You may change the side you play.

In addition, in the above explanation, it is assumed that 1.0 persons are irradiated with X-rays, but in an exposure apparatus where the wavelength distribution of X-rays differs depending on the position on the Be window, for example, an X-ray exposure apparatus with a swinging mirror is used for exposure. It may also be performed using X-rays. In that case, for example,
As shown in FIG. 5, in an X-ray exposure device with a mirror swing, the amount of X-ray irradiation is determined at the thickest point of the Be window at the same height and at the same position y. All you have to do is determine the rocking speed of the mirror.

(Effects of the Invention) As described above, the present invention involves coating a negative photosensitive film on one side of the Be film of the X-ray extraction window, irradiating X-rays from the opposite side of the film, and then developing the film. The uniformity of the X-ray transmittance of the X-ray extraction window was achieved by using the Be Even in this case, by applying the manufacturing process of the present invention, the intensity of X-rays transmitted through this Be window can be made uniform within ±2%.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the manufacturing process of an X-ray extraction window according to a first embodiment of the present invention. FIG. 2 is a diagram showing a characteristic curve of a negative resist. FIG. 3 is a diagram showing a portion of the X cotton take-out window in FIG. 1. FIG. 4 is a diagram showing the manufacturing process of the present invention and the X-ray intensity before and after. FIG. 5 is a diagram in which the present invention is applied to a mirror-oscillating type SR exposure apparatus. FIG. 6 is a diagram showing a general X-ray exposure apparatus. 1: X-ray extraction window 3: Be film 11 + SR ring 13: Exposure chamber 2: Flange 4; Photosensitive coating 12: X-ray mirror 14: Vacuum partition Figure 2 Figure 3 Figure 4

Claims (5)

[Claims] (1) A method for producing an X-ray extraction window characterized by including a uniformization step of applying a photosensitive film to one side of the X-ray extraction window, irradiating an exposure light beam from the opposite side of the coated surface, and then developing it. . (2) X according to claim 1, wherein the homogenizing step is repeated multiple times.
How to make a wire extraction window. (3) The method for producing an X-ray extraction window according to claim 1 or 2, wherein the exposure light is synchrotron radiation. (4) The number of repetitions n of the homogenization process repeated multiple times determines the γ value of the photosensitive resin, the initial film thickness Ti, the linear absorption coefficient μ_R of X-rays, the average thickness t_V of the X-ray mask substrate, and the minimum Thickness t_m_i_n and linear absorption coefficient μ_W of mask substrate
Therefore, n≧(ln0.02−ln{μ_M(t_V−t_m_
i_n)})/(ln(1-0.434×γ×Ti×μ
_R)) The method for manufacturing an X-ray extraction window according to claim 2. (5) An X-ray exposure apparatus having an X-ray extraction window produced by the process according to any one of claims 1 to 4.