JP2544645B2 - Light reaction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a photoreaction device for decomposing a reaction gas by photoexcitation and performing reactions such as CVD, etching, and epitaxial crystal growth necessary for semiconductor device production. It is about.

[Conventional technology]

Until now, “Sy
chrotron Radiation Excited CVD and Etching "Tsuneo
Urisu, Hakaru Kyuragi, J.Vac.Sci.and Teeh.B5.1987.P1
The one disclosed in 436 is known. This uses an electron synchrotron radiation device with a wide spectral bandwidth as a light source.When a reaction gas is flowed in a reaction vessel and vacuum ultraviolet light from the radiation device is applied to the reaction gas, various types of substrate surfaces are exposed. A photoreaction can be induced. For example, if SiH ₄ gas is flowed, amorphous silicon, polysilicon, or silicon single crystal is deposited on the substrate. Further, if a gas containing carbon such as CH ₄ is passed, a carbon film is deposited. When etching gas such as SF ₆ and NF ₃ gas is flowed, semiconductors, metals, insulating films, etc. can be etched.

[Problems to be Solved by the Invention]

By the way, these reactions largely depend on the wavelength of the irradiation light. In particular, short-wavelength light of 50 Å or less plays an important role in the deposition of carbon film. Therefore, when it is desired to deposit a carbon film, it is necessary to irradiate with light including this short wavelength light. On the contrary, when it is desired to remove the Si crystal growth or the natural oxide film on the silicon substrate by etching, the deposition of carbon is an undesired factor, so cut short wavelength light of 50 Å or less, It is desirable to cause the reaction only with long wavelength light. The selection of the wavelength according to the reaction is important in the photoreaction using vacuum ultraviolet light, especially electron synchrotron radiation.

Therefore, in the prior art, in consideration of the wavelength dependence of the reaction, it has been proposed to use a multilayer reflection mirror to select a wavelength that is convenient for the reaction, but the entire optical system that guides light from the light source to the reaction container is proposed. The light intensity at
There is a problem in terms of efficient use of light, and the problem that the reaction rate decreases when light is attenuated has also arisen, and no measures have been proposed for these problems.

Therefore, the present invention solves the above-mentioned problems,
It is an object of the present invention to provide a photoreaction device that realizes an optical system in which the wavelength is selected according to the type of reaction and the loss of light intensity is minimized.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a first curved reflecting mirror that reflects a vacuum ultraviolet light beam emitted from a light source, and a reaction container that reflects the reflected light reflected by the first curved reflecting mirror again. A second plane reflection mirror or a curved reflection mirror, which guides the vacuum ultraviolet light beam to an incident portion of the reaction container by the first curved reflection mirror or the first and second reflection mirrors. Illuminated, the second plane reflection or curved reflection mirror is rotatably provided about an axis orthogonal to the optical axis, and the reaction container is rotated with the rotation of the second plane reflection or curved reflection mirror. The installation position is variable according to the change in the traveling direction of the reflected light.

Further, in order to achieve the above-mentioned object, the present invention re-reflects the first curved reflecting mirror that reflects the vacuum ultraviolet light beam emitted from the light source, and the reflected light reflected by the first curved reflecting mirror again. A second plane reflection mirror or a curved reflection mirror, which is guided into the reaction container, and the vacuum ultraviolet light beam is incident on the reaction container by the first curved reflection mirror or the first and second reflection mirrors. A plurality of mirrors which are focused on the second flat reflecting or curved reflecting mirror and which are arranged in the mirror chamber and are exchanged without breaking the vacuum of the mirror chamber according to the wavelength region desired to be selected. On the surfaces of these mirrors, thin films of two kinds of substances having different optical constants for soft X-rays are alternately laminated, so that a predetermined light beam with a predetermined incident angle can be obtained. It is what is done to increase or attenuate the reflectance in the wavelength region.

[Action]

In the present invention, since the vacuum ultraviolet light beam emitted from the light source is condensed at the incident portion to the reaction container by the reflection mirror, the diameter of the incident portion can be made small and the inside of the mirror chamber of the reaction gas can be reduced. It is not necessary to provide a window material as a vacuum partition in the incident part in order to prevent the light from flowing into the window, so that the loss of light by the window material is made zero.

Since the second reflecting mirror is rotated to select the wavelength and the reaction container is moved following the change in the traveling direction of the reflected light accompanying the rotation of the mirror, a total of two reflecting mirrors are used. It is possible to perform wavelength selection by condensing light only.

Further, by disposing a plurality of second reflecting mirrors in the mirror chamber and exchanging and using them according to the wavelength region to be selected, wavelength selection is performed without breaking the vacuum.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a block diagram showing an embodiment of a photoreaction device according to the present invention, in which 1 is an electron synchrotron radiation device as a light source for emitting a vacuum ultraviolet light beam L, and 2 is the light beam L.
The first curved reflection mirror 3 for reflecting and condensing light is arranged rotatably about an axis orthogonal to the optical axis, in other words, in a plane including the paper surface. The second reflection mirror that re-reflects the reflected light L'reflected by the mirror mirror 4, the mirror chamber 5, the reflection container 5, the nozzle for ejecting the reaction gas G, 7 the substrate holder, 8 the substrate,
Reference numeral 9 is an incident part that connects the mirror chamber 4 and the reaction container 5. The installation position of the reaction container 6 is configured to be rotated following the change in the traveling direction of the reflected light L ′ accompanying the rotation of the second reflection mirror 3. Therefore, the rear half portion 4A of the mirror chamber 4 is connected to the front half portion 4B via the flexible connecting member 10 so as to be rotatable in the arrow direction, and the same rotation as the second reflecting mirror is achieved. When the mirror 3 has a center of motion and rotates by a predetermined angle, it double-turns in the same direction,
Thereby, the installation position of the reaction vessel 5 can be changed.

In the case of the present embodiment, as the second reflecting mirror 3, an example of using a plane reflecting mirror is shown, but a curved reflecting mirror including a toroidal mirror having a predetermined curvature or a parabolic mirror may be used. The light beam L is focused on the incident portion 9 by the first curved reflecting mirror 2. in this case,
When the second reflecting mirror 3 is formed of a curved reflecting mirror, the first and second curved reflecting mirrors 2 and 3 collect the light on the incident portion 9. When the light beam L is condensed in this way,
The diameter of the incident part 9 can be made as small as possible (for example, about 1 mm × 1 mm), whereby the vacuum exhaust conductance of this portion of the reaction gas G is sufficiently small, and the mirror chamber 4 and the reaction container are so-called by differential exhaust. A large vacuum degree difference can be maintained during the period 5. By the way, it is also possible to raise the vacuum degree of the reaction vessel 5 to 10 ^-1 torr or more while maintaining the vacuum degree of the mirror chamber 4 at about 10 ^-8 torr. For this reason, the incident portion 9 is not provided with a window member for confining the reaction gas G in the reaction container 5 and preventing the reaction gas G from flowing into the mirror chamber 4, thus forming a low loss optical system. To do.

When a reaction gas G is flown into the reaction container 5 and is irradiated with a vacuum ultraviolet light beam L, various photoreactions can be induced on the surface of the substrate 8 as described above, and these photoreactions have the wavelength of the irradiation light. Heavily depends on. Therefore, it is important to select the wavelength according to the reaction.

Therefore, as the method of selecting the wavelength, in the embodiment shown in FIG. 1, the second reflection mirror 3 is rotated in the direction of the arrow to change the incident angle to change the wavelength component of the light beam L. There is.

That is, this embodiment utilizes the fact that the reflectance spectrum of the reflecting mirror has a short wavelength limit depending on the incident angle. For example, in the case of a platinum-coated reflecting mirror, when the incident angle is 85 °, the solid line a in FIG. There is a short-wavelength limit of reflectance as shown in, and this short-wavelength limit moves to the long-wavelength side as the incident angle of the reflection mirror becomes smaller. Therefore, the light emitted by changing the incident angle to the reflection mirror 3 is irradiated. The wavelength component of can be changed. In this case, if the second reflecting mirror 3 is not only rotated at that position but is also rotated in the left-right direction parallel to the optical axis at the same time, the movement amount of the configuration downstream of the mirror 3 is moved. Can be made smaller.

With the above configuration, it is possible to select the wavelength component of the light beam L and induce the photoreaction. However, instead of applying the platinum coat to the second reflecting mirror 3, the optical constant for the soft X-ray is changed. It is possible to reduce the loss of irradiation light and increase the reaction efficiency by alternately forming multilayer thin films made of two kinds of substances that are greatly different from each other.

That is, as described above, when the incident angle of light on the platinum-coated reflecting mirror is set to 85 °, the reflectance spectrum becomes as shown by the solid line a in FIG. 2, and the light having a wavelength shorter than about 20 A should be blocked. You can However, as is clear from the figure, since the short wavelength end of the spectral distribution has a gentle slope, the reflectance for the necessary light is low at this slope b, and there is much waste. On the other hand, it consists of two kinds of elements such as a light element and a heavy element whose optical constants greatly differ from those of soft X-rays, for example, WC, W-Be, Mo-Be, Pt-C and Mo-Si. A multilayer film in which thin films are alternately laminated with a predetermined thickness has a characteristic that it has a peak at a constant wavelength λ ₀ determined by the cycle of the laminated structure and gives a high reflectance mainly over a predetermined spectral bandwidth determined by the number of laminated layers. Have. Therefore, by coating and forming this soft X-ray multilayer film on the second reflection mirror 3 and adjusting the period and the number of layers, when the multilayer film is not attached, as shown by the broken line c in FIG. The inclination at the short wavelength end of the reflectance spectrum can be made steep so that the peak wavelength P of the black diffraction peculiar to the multilayer film exists at or near the inclined portion b of the mirror.
Therefore, it is possible to reduce the light loss of the wavelength component necessary for the reaction. In this way, the standard for improving the reflectance spectrum distribution is to design the multilayer film structure so that the wavelength λ ₀ determined by the stacking period falls within the wavelength region of the short wavelength end inclined portion of the reflectance spectrum distribution.

FIG. 3 is a block diagram showing another embodiment of the present invention. In this embodiment, a plurality of, for example, three second reflecting mirrors 3A, 3B, 3C corresponding to the wavelength region to be selected are provided in the mirror chamber 4.
It is arranged inside and configured to be selectively used as necessary. The second reflecting mirrors 3A, 3B, 3C are movable in the directions of the arrows, and are arranged at predetermined intervals on a support bar 13 having both ends penetratingly supported by the mirror chamber 4, and the support bar 13 is externally mounted. When the mirror chamber 4 is moved, it is replaced without breaking the vacuum in the mirror chamber 4 and installed in the optical path. The above-mentioned soft X-ray multilayer film is formed on each of the reflection mirrors 3A, 3B, 3C in accordance with the wavelength region desired to be selected. The incident angle of the light beam L on the second reflection mirrors 3A, 3B, 3C is constant, and the reaction container 5 is fixed.

Even with such a configuration, the same effect as that of the above embodiment can be obtained.

〔The invention's effect〕

As described above, in the photoreactor according to the present invention, it is possible to perform wavelength selection depending on the type of reaction, and it is possible to realize an optical system in which the loss of light intensity is reduced as much as possible, and thus an undesirable reaction It is possible to provide a photoreaction device having high reaction controllability and reaction efficiency by suppressing the reaction, and increasing the desired reaction rate, and it is possible to provide a CVD, photoetching, photoepitaxial crystal required for semiconductor device manufacturing. It is suitable for use in growth and the like.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing a spectral distribution of reflectance of a reflecting mirror, and FIG. 3 is a diagram showing another embodiment of the present invention. 1 ... Electron synchrotron radiation device, 2 ... first curved reflecting mirror, 3 ... second reflecting mirror, 4 ... mirror chamber, 5 ... reaction container, 8 ... substrate, 9 ... Incident part.

Claims (4)

(57) [Claims] 1. A first curved reflecting mirror for reflecting a vacuum ultraviolet light beam emitted from a light source, and a second curved reflecting mirror for reflecting the reflected light reflected by the first curved reflecting mirror into a reaction vessel. A plane reflection or a curved reflection mirror, wherein the vacuum ultraviolet light beam is condensed at an incident portion to the reaction container by the first curved reflection mirror or the first and second reflection mirrors, and The two plane reflection or curved reflection mirrors are rotatably provided about an axis orthogonal to the optical axis, and the reaction container is arranged in the traveling direction of the reflected light accompanying the rotation of the second plane reflection or curved reflection mirror. An optical reaction device characterized in that the installation position is variable according to changes. 2. The optical constant for soft X-rays according to claim 1, wherein both the first curved reflection mirror and the second plane reflection or curved reflection mirror or only the second plane reflection or curved reflection mirror have an optical constant for soft X-rays. Photoreaction characterized by increasing or attenuating the reflectance in a predetermined wavelength region with respect to a light beam having a predetermined incident angle by alternately forming thin films of two kinds of substances which are greatly different from each other. apparatus. 3. A first curved reflection mirror for reflecting a vacuum ultraviolet light beam emitted from a light source, and a second plane reflection for reflecting again the reflected light reflected by the first curved reflection mirror and guiding it into the reaction vessel. Or a curved reflecting mirror, wherein the vacuum ultraviolet light beam is focused on the incident portion to the reaction container by the first curved reflecting mirror or the first and second reflecting mirrors, and The plane reflection or curved reflection mirror is composed of a plurality of mirrors arranged in the mirror chamber and exchanged without breaking the vacuum of the mirror chamber according to the wavelength region to be selected. Is formed by alternately stacking thin films of two kinds of materials having different optical constants for soft X-rays, thereby increasing the reflectance in a predetermined wavelength region with respect to a light beam having a predetermined incident angle. Light reactor stomach, characterized in that the CPU 120 is configured to attenuate. 4. The multi-layer film structure of the second plane reflection or curved reflection mirror according to claim 2 or 3, wherein the reflection at the short wavelength end of the mirror reflectance spectrum distribution when the multi-layer film is not attached. The photoreaction device, wherein the material, period and number of layers of the multilayer film are set so that the peak wavelength of the black diffraction peculiar to the multilayer film exists at or near the slope of the rate spectrum distribution.