JPS61242022A - light irradiation device - Google Patents

Abstract

PURPOSE:To make the difference in pressure between a reflector chamber and an exposure chamber exceed two figures by a method wherein the positions of rotary center, rotary bangle of a reflector and a fixed slit are arranged so that reflecting beams may pass through the fixed slit constantly regardless of the rotation of reflector. CONSTITUTION:Incident beams 2 reflected by a reflector 1 arranged inside a reflector chamber 6 advances along a reflecting optical path through a beam duct 7 and a slit 8 to irradiate the surface of an irradiated material 11 arranged in a exposure chamber 9. Next the reflector 1 forms a reflecting angle of 85 deg.-87 deg.; the distance from the rotary center 4 to the reflecting point on reflector 1 is kept at 229-382mm; a differential exhausting slit 8 is located on a point 2.8mm distant upstream and 19.806mm distant downward respectively from the rotary center 4. Finally the incident beam section of 100mmX10mum, the slit 8 opening of 100mmX24mum and the reflector surface of 160mmX100mm are respectively specified.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a light irradiation device C suitable for applications requiring large-area irradiation such as lithography, and in particular to a light irradiation device C suitable for use in a reflecting mirror used for beam scanning. The present invention relates to a light irradiation device equipped with a reflecting mirror scanning mechanism that provides an optical system suitable for differential pumping between a chamber and a chamber for an irradiated object.

[Background of the invention]

Synchrotron radiation light (hereinafter abbreviated as 80B) from an electronic storage ring has recently been seen as a promising light source for lithography in VLSI manufacturing or CVD (abbreviated as photoCVD) that utilizes photochemical reactions (19
Magazine published in 1983 "Ny-Clear Instruments"
and method (Nuclear Instrument
nts and M@thods) Volume 208” Volume 2
The paper “Study of X-ray irradiation using a flat scanning mirror (INtll!t8TIGATIONO)” on pages 81 to 286
FX-R entry Y II! 1XPO8URE tJ8I
NG PLANFl SC entry NNINGMI RRO
R8) See J) 0 However, in putting this into practical use, there are two problems as described in the first section.

First, in current electron storage rings, the angular divergence of the SOR in the direction perpendicular to the orbital plane is at most l γ (γ-B/mC', where E is the kinetic energy of the electron, m is the rest mass of the electron, Since C is approximately the speed of light in vacuum) and the beam size of the electron orbit is small, only a minute area can be irradiated as is. On the other hand, phosphorography and photo-CVD require large area irradiation of ~100 m x 100 iu.

Second, in the electronic storage ring that is the light source,
In order for the stored electrons to have a sufficiently long lifetime, they must be placed in an ultra-high vacuum, whereas the light irradiation equipment coupled to this, for example in the case of X-ray lithography, generates a large amount of gas from the resist. In addition, in the case of photo-CVD, it is necessary to fill the material gas for semiconductors on the order of several Torr.

In order to put phosphorography and optical CVD into practical use using 08OR, which inevitably requires a low vacuum, it is necessary to solve the above two problems at the same time.

In the conventional device using 80R, for example, Handboo
k on 5ynchrotron Radio
n vol, IChapter 13. r8ync
hrotron Radiation X-Ray
Lithography J, and Nuc, supra.
l@arInstrum@nts and Metho
ds 208 (1983) 281, a method is adopted in which the beam is expanded using a convex reflector placed between the light source and the object to be irradiated, or a rotating plane reflector.

According to this method, the first problem mentioned above is solved, but
Since the beam is expanded downstream from the reflector, a microslit is interposed between the storage ring, the reflector chamber, and the light irradiation chamber under ultra-high vacuum, and both sides of the slit are differentially pumped. This makes it difficult to keep one side at ultra-high vacuum while the other at low vacuum.

That is, in the prior art, the tracing and light irradiation chambers have almost the same degree of vacuum, and the second problem mentioned above cannot be solved.

For example, if you try to perform phosphorography in this state,
The object to be processed must be one that does not generate gas even when irradiated, which is a very restrictive process.
Furthermore, it is impossible to apply it to optical CVD.

On the other hand, in the known example, in order to solve this problem, a method has been devised in which the reflecting mirror and the irradiation chamber are vacuum-isolated using a vacuum partition.

However, even in this case, there are no window materials that have high transmittance and high reliability for light in the soft X-ray region, which is important as irradiation light, so there are significant restrictions on the wavelengths that can be used. There remains the big problem of not being able to do so.

Also, suppose that the first problem is solved by widening the angle of the storage ring's electron orbit and by putting into practical use an 80R electron beam with a large electron beam size, and it becomes possible to directly irradiate a large area without using a reflector. However, since the low vacuum of the irradiation chamber and the ultra-high vacuum of the storage ring must be connected in some way, the second problem still remains.

[Purpose of the invention]

It is an object of the present invention to solve the above-mentioned vacuum problems in a light irradiation device consisting of a light source containing parallel soft X-rays, a reflector chamber equipped with a light scanning reflector, and an irradiation chamber. An object of the present invention is to provide a light irradiation device equipped with a plane reflecting mirror scanning mechanism capable of irradiating light over a large area.

[Summary of the invention]

The present invention is characterized by a reflecting mirror that is rotated by a predetermined angle around a straight line perpendicular to a plane that includes the incident optical path to the mirror surface and the reflected optical path, and a reflecting mirror that is incident from a fixed direction and reflected by the reflecting mirror. In a light irradiation device having a fixed slit to pass through and an exposure chamber in which an object to be irradiated is housed, the rotation center position and rotation angle of the reflecting mirror and the position of the fixed slit are determined by the reflecting mirror. Regardless of the rotation of the slit, the reflected light is always set to substantially pass through the fixed slit.

Another feature of the present invention is that the light source for incident light, the reflecting mirror storage section, and the exposure section chamber are configured to be differentially pumped.

[Embodiments of the invention]

The principle of the mirror scanning mechanism in the present invention will be explained with reference to FIG.

By the reflecting mirror 1, the incident light 2 is reflected in the direction shown by the optical path 3.The OX axis is set in the direction that coincides with the incident light 2, and the rotation center 4 of 1 reflection*1 is set from the X axis on the extension of the reflecting mirror 1.
Also, take a straight line passing through the center of rotation 4 of the reflecting mirror and perpendicular to the X-axis as the y-axis.

At this time, the coordinates of the mirror rotation center 4 are (o+yo), and the coordinates of the reflection point of the light beam on the plane mirror are (yota
nθ, 0).

In the younger brother 1 diagram, X-ξ. Assuming straight line 5,
Coordinates (ξ., V) of the intersection S of this straight line 5 and the reflected optical path 3
is the incident angle θ (the normal to the reflecting surface of the reflecting mirror l and the incident light 2
), the center of rotation 4 is y.

(ξo, v) = (ξ0.tan2θ(ξ6-76tan
θ))...(1) Here, the reflector 1 is θ-θ.

If it is centered at , and rotates to both sides by a small angle of Δθ, then by Taylor expansion in the vicinity of θ0 with respect to θ, l becomes 〇η(θo
)=tan2θ. ×(ξ.-3'o tanθ.) Song・
・(3)-y. sin 2θ0) 藺...(5) now ξO
If we select I 0 so that the relationship ξo-76sin 2θ0 is satisfied, then from equation (4).

is expressed by the following equation (6).

l(θ.+Δθ) = 276 sin”θ.

As is clear from the above equation, θ-θ with the reflecting mirror 1 as the center (osyo) point 4. When the reflected light is scanned and rotated by rotating it by a minute amount of ±Δθ, the reflected optical path 3 is approximately one point S(ξ., η(θ.)), that is, (y0sin2θo v 2y6ainθ). )...
・・・・・・・・・(7) can be considered to always pass through 0 In the present invention, by placing a slit for differential pumping at an approximate fixed point of the reflected optical path whose existence was shown by the above proof, The reflected light passing through the differential pumping slit performs differential pumping between the reflecting mirror section and the exposure section.The reflecting mirror rotates about the point 4 in FIG. 1.

θ. By rotating ±Δθ on both sides, ±2・Δ
In the above proof, the angle of incidence θ0 and the center of rotation (O+
Assuming that yo) is known, a fixed point (ξ0゜l(θ.)
), but it goes without saying that any two of these three must be determined first, and then the remaining one must be determined.
It will be clear that it is possible to define two quantities. FIG. 2 is a schematic block diagram showing an example of applying the principles of the present invention to a soft X-ray phosphorography apparatus.

In the figure, the same reference numerals as in FIG. 1 are used.

The same or equivalent parts are hailed.

In this example, as a concrete numerical example, the reflection angle θ in FIG. yo in FIG. 1 was set to 20U.

Then, the differential pumping slit 8 is placed at the coordinate point of equation (7) - that is, at a point 2.8+u upstream and 19.806mm away from the rotation center 4 of the reflecting (scanning) mirror 1. installed.

In the case of the above numerical example, the variation in the position of the reflected light on the slit for rotational scanning of ±1° is less than 14 μm. Therefore, it is possible to use a slit with a width of about 14 μm as the differential pumping slit 8. . This value is sufficient to maintain the ultra-high vacuum required in the toslasing and reflector chamber 6 and the low vacuum required in the exposure chamber 9. The distance to the reflection point on mirror l varies within the range 229IIx to 382Nx. This means that the minimum length of the (scanning) reflector 1 is 15
This means that 3 m (=382-229) is required, which is also a size that can be put to practical use.

In FIG. 2, incident light 2 is reflected by a reflector 1 placed inside a reflector chamber 6, and is reflected by a beam duct 7.
The light beam passes through the slit 8 along the reflected light path 3 and irradiates the surface of the irradiation material 11 placed in the exposure chamber 9 .

In this example, the size of the incident light beam cross section is 10
Set to 0 w x 10 μm, and slit 8 for differential pumping.
The size of the opening was set to 100w x 24μm. Further, the size of the reflecting mirror surface was set to 160w x 100mm.

As a result, all of the reflected light was able to reach the exposed portion ζ without being blocked by the slit.
When the distance was set to 1500 m, the irradiation area was 100 iw x 107 m.

Further, the reflector chamber 6 and the exposure chamber 9 are evacuated by separate vacuum pumps 10B and 10B, respectively. The pumping speed of the vacuum pump is 4004/! It is I.

As a result, the degree of vacuum in the exposure chamber 9 is 1.4×10
-'Torr, the vacuum level inside the reflector chamber 6 could be maintained at lXl0 Torr due to the effect of differential pumping.
According to this embodiment, the degree of vacuum in one reflecting mirror chamber 6 is improved by more than two orders of magnitude compared to the conventional method.
This means that the life of the reflector is substantially extended by more than 100 times.

The present invention is applicable not only to phosphorography but also to other irradiation devices, and an example in which the present invention is applied to optical CVD using an o soa light source is shown in FIG.

In this case, the source gas for CVD is introduced into the exposure chamber 9 containing the irradiation material 13, and the source gas is decomposed by the reflected light 3L.

Since the pressure inside the exposure chamber 9 is normally reduced to 10 Torr, cylindrical concave mirrors 12A, 12 whose cross section is a part of an ellipse are provided between the reflector chamber 6 and the exposure chamber 9.
A plurality of (two stages in this example) differential pumping is employed, which is a combination of B and slits 8A and 8B.

That is, in the third cause, there are 12 cylindrical concave mirrors.

The reflective concave surface 12B is part of an ellipse, and the two focal points of the ellipse are made to coincide with the front and rear slits 8, 8 or 8B, respectively. As shown, the light 3L deflected and reflected by the (scanning) reflector 1 can be effectively regarded as diverging light emitted from the slit 8, so 12 cylindrical concave reflectors are used to transmit 8 lights above the downstream slit. It is possible to form an image.

The same applies to the cylindrical concave reflecting mirror 12B, and the diverging light from the 8 slits on the upstream side is reflected from the 8B slits on the downstream side.
In the embodiment of FIG. 3, 12 cylindrical concave reflectors are focused on.

As 12B, a cylindrical concave mirror with a radius of curvature of 1 m is used,
As mentioned above, this concave mirror has 8 slits, 8 people, and a distance of 139u between 8B and the center of the concave mirror.
It is desirable to use a cylindrical concave reflector with an elliptical cross section, but in practice, a concave mirror with a quadratic cross section may be used instead. In this embodiment, as in the first embodiment, The size of the incident light beam cross section is 100 m x 10 μm, the incident angle θ is scanned between 87° and 85°, and the opening size of slit 8 is set to 100 w x 25 μm. In this case, the irradiation area is 100 w x 107 be.

Furthermore, by evacuating three stages of differential pumping with vacuum pumps each having an evacuation speed of 400 t/s, when the pressure in the exposure section chamber 9 is 10 Torr, the pressure in the (scanning) reflector section chamber 6 is I x 10-8 Torr.

In this example, since the photoCVD reaction tank and the light source can be combined without a transmission window, the reaction products do not accumulate on the transmission window, and stable irradiation for a long time is possible. The operating rate of the device can be significantly improved.

FIG. 4 shows an embodiment in which the present invention is applied to optical CVD using an ordinary mercury lamp or the like as a light source.

The light from the light source 14 is guided into the reflector chamber 6 through the entrance window 15 and is reflected by the (scanning) reflector 11 in the direction of the reflection beam path 3 . This reflected light passes through a slit 8 provided between the reflector chamber 6 and the exposure chamber 9, irradiates and decomposes the source gas in the exposure chamber 9, and deposits a reaction product on the substrate 13.

In the embodiment shown in FIG. 4, since the pressure of the raw material gas in the exposure chamber 9 exceeds several Torr, an inert gas is added in the reflector chamber 6 to prevent the raw material gas from flowing into the reflector chamber 6. filled with.

In this example, the incident angle θ was scanned at (45±2), that is, between 43° and 47°, and the opening of the slit 8 was set to 100w×100μm. Also, slit 8
The distance from the substrate 13 to the substrate 13 was set to 700U, and the irradiation area was set to 100w x 100m.

In this example, since the entrance window 15 and the reflecting mirror 1 are not exposed to high-concentration source gas, the deposition of reaction products on the entrance window and the reflecting mirror is extremely small, making it possible to irradiate for a long time. It is. As a result, as in the case of FIG. 3, the operating rate of the apparatus can be improved.

〔Effect of the invention〕

According to the present invention, in light irradiation using a parallel light source including soft X@, a pressure difference of two orders of magnitude or more can be easily achieved between the reflector chamber and the irradiation or exposure chamber without using a vacuum partition This has the effect of irradiating a large area with all light having a wavelength longer than soft X-rays without losing the amount of light or limiting the material of the object to be irradiated.

Furthermore, the slit installed downstream is effective in removing stray light on the light source side, and has the effect of reducing scattered light harmful to irradiation.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the principle of a mirror scanning mechanism according to the present invention. FIG. 2 is a schematic side view of an embodiment of the present invention. FIG. 3 is a schematic side view of another embodiment of the invention. FIG. 4 is a schematic side view of yet another embodiment of the invention. 1... (scanning) reflecting mirror, 2... incident light, 3... reflected optical path, 4... reflecting mirror rotation center, 5... straight line X"X
Q. 6...Reflector chamber, 7...Vacuum duct, butt...
Slit, 9... Exposure section chamber, 1o... Vacuum pump, 11... Irradiation material, 1274. , 12 B.
... Cylindrical concave reflecting mirror, 13... Substrate, 14... Light source, 15... Entrance window, 19... Reaction chamber agent Michihito Hiraki, patent attorney Figure 1 1JB

Claims (3)

[Claims] (1) A reflecting mirror that is rotated by a predetermined angle around a straight line perpendicular to a plane that includes the incident optical path and reflected optical path to the mirror surface, and a fixed fixture through which reflected light that is incident from a fixed direction and reflected by the reflecting mirror passes. In a light irradiation device including a slit and an exposure chamber in which an object to be irradiated is housed, the rotation center position and rotation angle of the reflecting mirror and the position of the fixed slit are determined by the rotation of the reflecting mirror. Regardless of the above, the light irradiation device is characterized in that the reflected light is set to substantially always pass through the fixed slit. (2) In the plane of rotation of the reflecting mirror, the direction of the light incident on the reflecting mirror is the x-axis, and the direction from the center of rotation of the reflecting mirror to the x
When the perpendicular direction to the axis is the y-axis, the angle that the reflecting mirror makes with the y-axis at its center position is θ_0, and the coordinates of the center of rotation are (0, y_0), the fixed slit is at the coordinate position ( y_0sin2θ_0, 2y_0s
The light irradiation device according to claim 1, wherein the light irradiation device is set to in^2θ_0). (3) The light irradiation device according to claim 1 or 2, characterized in that the light source for incident light, the reflecting mirror storage section, and the exposure section chamber are differentially pumped out by the fixed slit. .