JPH0638392B2 - Surface treatment device using synchrotron radiation - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a surface treatment apparatus that transfers a pattern onto a sample by using synchrotron radiation, or performs etching / film forming treatment on the sample surface, and particularly, on a vacuum side. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment apparatus using radiant light, which has an improved radiant light transmitting window for guiding the radiant light to the atmosphere side.

[Technical background of the invention and its problems]

In recent years, with the miniaturization of semiconductor elements, there is an increasing possibility that X-ray lithography will be used instead of optical lithography in the manufacturing process thereof. As an X-ray source in X-ray lithography, there are a normal X-ray tube, a synchrotron source, and the like. In particular, the latter has much higher throughput, almost no penumbra part, and higher contrast than the former. In particular, attention is paid to the reason that a thicker resist can be used.

The emitted light from the synchrotron source is emitted from the electron flow in the ultra-high vacuum, but at the location where the X-ray mask is brought close to the wafer to expose the resist, the temperature rise of the X-ray mask due to the emitted light is suppressed, A state close to the atmosphere is desirable in order to facilitate the alignment / transfer system operation of the mask and wafer. Therefore, a window is required to separate the vacuum on the radiation side and the atmosphere on the exposure side. The requirements for this window are easy to understand,
It has sufficient mechanical strength and transmits radiation of useful wavelength. These conditions have mutually opposing properties, and it is extremely difficult to satisfy them together. In practice, the radiation transmitting window is made of a material composed of a low atomic weight element that absorbs little radiation, for example, a thin film such as a metal beryllium film or a Kapton organic film.

On the other hand, when the electrons travel in a horizontal orbit, the emitted light obtained is a light flux that is uniform in the horizontal direction and has a width of about 5 [mm] in the vertical direction. Therefore, in order to uniformly irradiate a large area of a semiconductor wafer with radiated light, a reflection mirror of the radiated light is oscillated so that the light flux is oscillated in the vertical direction, or a mask / wafer system is used. It is necessary to move it mechanically.

Also, from the viewpoint of strength, the thin window for reducing the above absorption is a cylindrical surface having a curved surface rather than a flat plate fixed at the periphery, or
Furthermore, it is advantageous to use a spherical surface, and in that case, it is advisable to make the radius of the spherical surface or the cylindrical surface as small as possible. However, it has been found that a curved surface having a substantially uniform thickness manufactured by bending a flat plate or performing simple deep drawing has the following problems. That is, in the case of the spherical window, the center of the resist portion to be exposed is sufficiently exposed, but the exposure becomes insufficient toward the periphery. In the case of a cylindrical surface, the exposure amount decreases from the center as the distance from the axis of the cylinder increases. As a result of investigating the cause, the curved portion is perpendicular to the radiated light at the center of the curved window, but the curved portion becomes inclined with respect to the radiated light toward the periphery, and the transmitted thickness of the radiated light is It turned out to be to increase. Further, this result was more remarkable as the radius of the spherical surface or the cylinder was smaller.

The above-mentioned problem is not limited to the pattern transfer device, and the same applies to various surface treatments in which irradiation of radiant light is used to etch the sample surface or form a film on the sample surface.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to uniformly irradiate radiated light through the window even though a curved radiant light transmissive window is used. Another object of the present invention is to provide a surface treatment device using synchrotron radiation.

[Outline of Invention]

The essence of the present invention is to make the optical path length of radiated light in the window material completely equal by varying the thickness of the window formed of the curved shell (the vertical thickness of the curved surface).

That is, in the present invention, the radiation source is arranged on the vacuum side, the sample is arranged on the atmosphere side, the vacuum side and the atmosphere side are separated by the radiation light transmission window, and the radiation light from the radiation light source is passed through the radiation light transmission window. In the surface treatment device for irradiating the sample surface with a predetermined treatment, the radiant light transmission window is formed by a part of a thin curved shell, and the thickness of the curved shell in the transmission direction of the radiated light is Are formed equally in each part.

Now, the outline of the present invention will be further described with reference to FIG. For the sake of simplicity, a sphere and a cylinder are assumed as curved surfaces, the inner diameter thereof is r, and the thickness t in the direction perpendicular to the surface at the angle θ from the center is t = t ₀ · cos θ. However, t ₀ is the thickness at the center. By doing so, in the approximation of the thin-walled shell, the optical path length of the radiated light, which is almost a parallel beam, becomes t ₀ at all positions, the absorption of the radiated light by the window becomes uniform, and uniform radiated light irradiation is possible. become. Usually, a hemispherical surface or a semi-cylindrical surface is not used, and the maximum θ _M is 90 ° or less, in which case the vertical thickness is the minimum. The thickness t _M = t ₀ cos θ _M at the maximum angular position may be selected as a safe value in consideration of the magnitude of the atmospheric pressure, the radius of the sphere or cylinder, the tensile strength of the window material, and the like.

〔The invention's effect〕

According to the present invention, since the radiant light transmission window formed of the curved shell is used, the strength thereof can be increased as compared with the flat window. Conversely, it becomes possible to form the window thinly, and it is possible to reduce the absorption of the radiated light by the window. Further, by making the thickness of the window variable as described above, the optical path length of the emitted light in the window can be made equal at all positions. Therefore, the irradiation of the radiant light from the vacuum side to the atmosphere side can be performed uniformly.

Therefore, when applied to pattern transfer, uniform exposure can be performed. Further, when applied to surface treatment such as etching or film formation utilizing excitation by radiated light, the treatment can be performed uniformly.

Example of Invention

 Hereinafter, details of the present invention will be described with reference to illustrated embodiments.

FIG. 1 is a schematic configuration diagram showing a pattern transfer device according to an embodiment of the present invention. In the figure, 11 is a synchrotron (S
R), and the X-ray beam (radiation light) 12 emitted from this SR 11 is reflected upward by 45 [mrad] by the reflection mirror 13. This reflection mirror 13 is made of a quartz substrate
u is vapor-deposited and is vibrated in the direction of arrow P in the figure by the vibrating mechanism 14. Due to this vibration, the X-ray beam 12 is reciprocally deflected. Further, the cylindrical body 15 through which the X-ray beam 12 reflected by the reflection mirror 13 passes
And SR11 are maintained in an ultrahigh vacuum by a vacuum pump 16.

The X-ray beam 12 reflected by the reflection mirror 13 has a cylindrical body 15.
Radiation light transmitting window 1 which is hermetically closed at the tip opening of the
After passing through 7, it is introduced into the sample processing chamber 18 kept at atmospheric pressure. In the processing chamber 18, an X-ray mask 19 for pattern transfer and a semiconductor wafer 20 are arranged opposite to each other. The mask 19 is formed by forming a pattern made of an X-ray shield on an X-ray transparent substrate. The wafer 20 has an upper surface coated with a resist that is an X-ray photosensitive material. Then, the mask 19 is irradiated with the X-ray beam 12,
By scanning in the direction of arrow Q in the figure, the pattern of the mask 19 is transferred onto the wafer 20.

Here, the radiant light transmission window 17 is formed as follows.

First, a spherical mold having a radius of 3 [cm] was prepared, an evaporation source was placed above the mold so as to be sufficiently separated, and Be was deposited on the surface of the curved mold to form a curved shell of Be. Next, the curved shell was removed from the mold, and only a portion within a range of 45 degrees from the center was cut out to form a radiant light transmitting window 17 as shown in FIG. The thickness of the center of the window 17 was t ₀ = 12 [μm].
When the thickness t at each position (position at an angle θ from the center) was examined by an X-ray thickness meter, it was found that the relationship of t = t ₀ · cos θ was satisfied. That is, it was found that the thickness of the curved shell in the transmission direction R of the radiated light was the same in each part. This was attached to a flange having an inner diameter of 5 [cm] and arranged at the tip of the cylindrical body 15.

Next, the operation of the present apparatus configured as described above will be described.

First, as the X-ray mask 19, one having an opening pattern equal to the exposure area is used, or the mask 19 is separated from the position facing the wafer 20. A PMMA (polymethylmethacrylate) resist is applied on the wafer 20 in advance. The sample chamber 18 is filled with He gas at 1 atm. In this state, the X-ray beam 12 having a horizontal strip shape was irradiated onto the resist from the vacuum side, and the beam was moved at a constant velocity in the exposure area to expose the resist. Then, the wafer 20 was taken out of the sample chamber 18 and subjected to a predetermined developing process. The resist film thickness after development is shown by the solid line in FIG. From this figure, it can be seen that uniform exposure is performed over the entire exposure area.

On the other hand, instead of the radiant light transmitting window 17 shown in FIG.
The same exposure and development as described above was performed using a window of the same shape having a substantially uniform thickness of 12 [μm] obtained by deep drawing of the foil. The remaining thickness of the resist at this time is shown by a broken line in FIG. In this case, it can be seen that the resist residual film thickness becomes thicker in the peripheral portion, and the peripheral portion shows insufficient exposure.
This is because the effective optical path in the window of the X-ray beam 12 becomes longer in the peripheral portion, so that the absorption in the window in the peripheral portion increases.

As described above, according to this embodiment, since the thickness of the radiant light transmitting window 17 formed of the curved shell is formed so as to be uniform in each portion in the transmitting direction of the radiant light, the window 17 is transmitted. It is possible to uniformly irradiate the synchrotron radiation later. In this case, since the window 17 has a curved surface, the strength of the window 17 can be increased. Conversely speaking, the window 17 can be made thin, and the absorption of radiated light by the window 17 can be reduced. Therefore, a uniform pattern can be transferred over a large area with a high throughput, and its utility in the semiconductor manufacturing field is great.

4A and 4B show the configuration of the main part of another embodiment, wherein FIG. 4A is a side view, and FIG. 4B is a view taken in the direction of arrow AA of FIG. This embodiment is different from the above-described embodiments in that a curved shell having a cylindrical surface is used as the radiation transmitting window, and the other points are exactly the same.

The radiant light transmission window in this embodiment is formed as follows. That is, a Be plate having a thickness of 15 [μm] has a radius of 3
It was processed into a cylindrical surface of [cm], and a window-shaped window with 120 ° openings was produced. Next, chemical / mechanical etching was performed to reduce the vertical height from the center line to the periphery at approximately cos θ. The thickness around the periphery was about 8 [μm]. The PMMA resist was exposed in He gas at 1 atm through a window so that the center line was horizontal.

For comparison, exposure was also performed using a cylindrical window having a thickness of 15 [μm]. As a result, in the case of this example, a uniform residual film thickness was shown, but in the case of the comparative example, the same underexposure was shown from the center to the periphery in the vertical direction.

The present invention is not limited to the above-mentioned embodiments. For example, the curved shell that forms the radiation transmitting window is
The shape is not limited to a spherical surface or a cylindrical surface, and may be a parabolic surface or an arbitrary curved surface. Further, the material for forming the radiant light transmission window is not limited to Be at all, and any material that absorbs little radiated light may be used, and in general, it may be composed of a low atomic weight element. Further, in the above-mentioned embodiment, it was assumed that the emitted light was parallel rays near the window, and the film thickness dependence of cos θ was shown. However, if the distance between the reflection mirror and the window is short due to spatial restrictions, etc. The film thickness may be changed. Also,
The invention is not limited to pattern transfer, and can be applied to surface treatment by radiant light excitation in which a sample in a predetermined atmosphere is irradiated with radiant light to perform etching or film formation. In addition, various modifications can be made without departing from the scope of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a pattern transfer device according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing a thickness change of a radiant light transmitting window used in the device, and FIG. 3 is a diagram showing the device. FIG. 4 is a characteristic diagram for explaining the operation, and FIG. 4 is a diagram showing a main part configuration of another embodiment. 11 ... Synchrotron (SR), 12 ... X-ray beam (synchronized light), 13 ... Reflection mirror, 14 ... Vibration mechanism,
15 ... Cylindrical body, 16 ... Vacuum pump, 17, 47 ... Radiant light transmitting window, 18 ... Sample chamber, 19 ... X-ray mask, 2
0 ... wafer.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 21/31 B

Claims (4)

[Claims] 1. A radiation source is arranged on the vacuum side, a sample is arranged on the atmosphere side, the vacuum side and the atmosphere side are separated by a radiation light transmission window, and radiation light from the radiation light source is passed through the radiation light transmission window. In the surface treatment apparatus for irradiating a sample with a predetermined treatment on the surface of the sample, the radiant light transmission window is formed of a part of a thin curved shell and has a thickness of the curved shell in the transmission direction of the radiated light. A surface treatment device using synchrotron radiation, characterized in that each part is made substantially equal. 2. The curved surface shell is a spherical surface, and the distance from the radiation light source to the curved surface shell is made longer than the distance from the curved surface shell to the center of curvature thereof. A surface treatment apparatus using the synchrotron radiation described. 3. The curved shell is a cylindrical surface, and the distance from the radiation light source to the curved shell is longer than the distance from the curved shell to the center of curvature thereof. A surface treatment apparatus using synchrotron radiation according to the item. 4. The sample according to claim 1, wherein the sample is arranged so as to face a pattern transfer mask, and the radiated light is irradiated onto the sample through the transfer mask. Surface treatment device using synchrotron radiation.