JP3624523B2 - X-ray projection exposure apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is suitable for use in transferring a circuit pattern on a photomask (mask or reticle) onto a substrate such as a wafer via a projection imaging optical system by a mirror projection method using an X-ray optical system or the like. The present invention relates to a projection exposure apparatus.
[0002]
[Prior art]
An exposure apparatus for manufacturing a semiconductor projects and transfers a circuit pattern formed on a photomask (hereinafter sometimes abbreviated as a mask) as an object surface onto a substrate such as a wafer via an imaging optical system. . Here, a resist is applied to the substrate, and the resist is exposed by pattern exposure to form a resist pattern.
[0003]
FIG. 4 conceptually shows a configuration (part) of a general X-ray projection exposure apparatus (one example) used as an exposure apparatus for semiconductor manufacturing.
The exposure apparatus receives an X-ray source 1, an illumination optical system 2 that irradiates the mask 3 with X-rays 20 generated from the X-ray source 1, a stage 4 of the mask 3, and an X-ray 22 from the mask 3. Are formed by a projection imaging optical system (hereinafter sometimes abbreviated as an imaging optical system) 5 for projecting an image formed on the wafer 6 and a stage 7 of the wafer 6.
[0004]
X-rays are difficult to diffract with conventional lenses. Therefore, the illumination optical system 2 and the imaging optical system 5 are configured by a reflective optical system using a reflecting mirror. In particular, for X-rays with a wavelength of 13 nm, a multilayer film made of molybdenum and silicon has a high reflectance even at normal incidence, and thus the multilayer film is often provided on the reflecting surface of a reflecting mirror.
[0005]
The mask 3 is formed with an equal pattern or an enlarged pattern of a pattern drawn on the resist (on the substrate). A conceptual diagram (sectional view) of a mask (one example) is shown in FIG.
Like the illumination optical system 2 and the imaging optical system 5, the mask is preferably of a reflective type. Therefore, for example, the X-ray absorption layer 33 may be formed in a pattern on the X-ray reflective multilayer film 32 (formed) on the substrate 31 to form a reflective mask.
[0006]
In this way, the portion where the multilayer film 32 is exposed reflects the X-rays by the multilayer film, and the portion of the X-ray absorption layer 33 (hereinafter sometimes abbreviated as an absorption layer) formed in a pattern is the X-ray. Is absorbed and not reflected.
X-rays 20 generated from the X-ray source 1 are irradiated onto the mask 3 through the illumination optical system 2. Then, the X-rays 22 reflected by the mask 3 are irradiated (pattern exposure) to the resist on the wafer 6 through the imaging optical system 5. In this way, the pattern on the mask 3 is imaged on the resist on the wafer 6.
[0007]
In order to form a desired imaging pattern on a resist on a wafer (hereinafter sometimes abbreviated as “on the wafer”), at least the imaging optical system 5 is required to have near-aberration performance. The mask 3 is required to have no or very few patterns.
[0008]
[Problems to be solved by the invention]
However, even if a mask having no defect in the pattern is used, if dust that interferes with reflection of X-rays adheres to the mask reflection surface during exposure, a defect is generated in the pattern formed on the wafer.
For example, as shown in FIG. 5B, when the dust 34 adheres to the exposed portion of the multilayer film 32 on the mask, the dust 34 exhibits the same action as the absorption layer 33. That is, since the X-rays incident on the dust 34 are absorbed by the dust 34, the X-rays incident on the portion that should be reflected (multilayer film exposed portion) are not reflected.
[0009]
In general, an exposure apparatus for manufacturing a semiconductor is often installed in a clean room in order to prevent dust floating in the air from adhering to a semiconductor being manufactured.
However, it is almost impossible to completely eliminate the garbage in the clean room. Further, the exposure apparatus has sliding portions such as the stages 4 and 7, and dust may be generated therefrom.
[0010]
Therefore, the conventional exposure apparatus has a problem that dust adheres to the mask 3 and this makes it difficult to obtain a desired resist pattern.
The present invention has been made in view of such a problem, and can effectively prevent dust from adhering to the mask on which the pattern is formed. An object of the present invention is to provide an X-ray projection exposure apparatus that can effectively prevent a defect from occurring in a resist pattern formed in this manner.
[0011]
[Means for Solving the Problems]
Therefore, the present invention is "at least a first, a X-ray source, an illumination optical system for irradiating the photo mask disposed at a predetermined position of the X-ray generated from the X-ray source, a stage of the photomask, the A filter provided close to the photomask; a projection imaging optical system that receives X-rays from the photomask and projects a pattern formed on the photomask onto a wafer placed at a predetermined position; and In an X-ray projection exposure apparatus comprising a wafer stage,
The X-ray projection exposure apparatus characterized in that the filter has a slit-shaped X-ray transmission part that transmits X-rays, and a support part that supports the X-ray transmission part and does not transmit X-rays. 1) ".
[0012]
The X-ray projection exposure according to claim 1, wherein the projection imaging optical system has a zonal field of view and the X-ray transmission part has a zonal shape. An apparatus (Claim 2) "is provided.
According to a third aspect of the present invention, “ the shape and size of the X-ray transmission part is made equal to an effective field of view on a photomask of the projection imaging optical system. A line projection exposure apparatus (Claim 3) "is provided.
[0013]
Further, the present invention is "the X-ray transmitting portion Fourth, Be, Si, X-ray projection exposure apparatus according to claim 1 to 3, wherein the composed formed by Be compound, or a Si compound (according Item 4) ”is provided.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a conceptual diagram showing a configuration (a part) of an X-ray projection exposure apparatus (one example) according to the present invention .
The exposure apparatus shown in FIG. 1 receives an X-ray source 1, an illumination optical system 2 that irradiates a mask 3 with X-rays 20 generated from the X-ray source 1, a stage 4 of the mask 3, and an X-ray 22 from the mask 3. A projection imaging optical system 5 for projecting and imaging a pattern formed on the mask 3 onto a resist on the wafer 6, a stage 7 for the wafer 6, and a filter 8.
[0016]
Since the filter 8 is disposed between the mask 3 and the imaging optical system 5 in the vicinity of the mask 3, the dust adheres to the filter 8 even if dust floating in the space approaches the mask 3.
Therefore, according to the present invention , it is possible to effectively prevent dust from adhering to the mask on which the pattern is formed. As a result, the resist pattern formed corresponding to the mask pattern at the time of exposure is defective. Can be effectively prevented.
[0017]
The filter 8 is preferably disposed so as to prevent dust from adhering to the mask 3 as much as possible.
For example, as shown in FIG. 2A, the filter 8 may have a plate shape larger than the mask 3, and may be arranged close to each other so as to be parallel to the reflective surface 30 of the mask.
Here, if the distance between the filter 8 and the reflective surface 30 of the mask 3 is made too small and, as an extreme example, if the filter 8 is brought close enough to contact the mask 3, dust adhering to the filter 8 is reflected on the reflective surface of the mask 3. It will be in the same position as 30. In this case, a projection image of dust is formed on the wafer 6, which is not preferable.
[0018]
Therefore, the distance between the mask and the filter is preferably larger than the depth of focus on the mask side of the imaging optical system .
In this way, even if dust adheres to the filter 8, the projected image does not form on the wafer 6 and does not cause a defect in the resist pattern on the wafer.
The filter 8 is preferably larger than the mask 3 in order to increase the effect of preventing dust from adhering to the mask 3, but in this case, X-rays used for X-ray projection exposure are incident on the filter. Will do.
[0019]
Therefore, the filter according to the present invention preferably has at least an X-ray transmission portion that transmits X-rays used for X-ray projection exposure .
Therefore, for example, the filter 8 is made of a material having a high X-ray transmittance, and the entire filter is used as an X-ray transmission part, or an X-ray transmission part made of the material is provided in a part of the filter 8, and It is preferable to make the X-ray transmission part thinner with respect to the transmission direction of the X-ray 22.
[0020]
As a material constituting the filter or its X-ray transmission part (hereinafter, sometimes abbreviated as X-ray transmission part), Be, Si, which has a high X-ray transmittance and can be easily thinned or thinned. A Be compound or Si compound is preferred. In particular, these materials are preferable for X-rays having a wavelength of 13 nm.
If the X-ray transmission part is thinned or thinned, the strength of the X-ray transmission part may be reduced, which may be a problem. Therefore, the filter according to the present invention preferably has a support part for the X-ray transmission part .
[0021]
For example, as shown in FIG. 2B, in order to reinforce the strength of the X-ray transmission part 8a of the filter 8, a support part 8b that supports the X-ray transmission part 8a may be provided.
The support portion 8b does not necessarily have a high X-ray transmittance. At least the X-ray 21 directed from the illumination optical system 2 to the mask 3 and the X-ray 22 effective for imaging from the mask 3 to the imaging optical system 5 are used. It is only necessary to have a shape that does not obstruct the optical path.
[0022]
For example, when an optical system having an annular field is used for the projection imaging optical system 5, as shown in FIG. 3, a portion (X-ray transmission portion) 8a having a high X-ray transmittance in the filter 8 is used. It is only necessary to support the support member 8b so that the X-ray optical path effective for imaging is not formed.
Thus, it is preferable to reduce the area of the X-ray transmission part 8a and hold it by the support part 8b, since the thickness of the X-ray transmission part 8a can be reduced while increasing the strength of the entire filter 8.
[0023]
Here, if the shape of the X-ray transmitting portion 8a is a slit shape (for example, an annular shape) and the support portion 8b is a member that does not transmit X-rays or does not transmit X-rays effective for imaging, a filter can be used. 8 can have a slit effect .
That is, unnecessary X-rays that do not contribute to image formation can be removed from the X-rays 21 that are about to enter the mask 3 from the illumination optical system 2. As a result, the contrast of the imaging transfer pattern is increased, and a high-quality resist pattern can be obtained.
[0024]
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these examples.
[0025]
【Example】
FIG. 1 is a conceptual diagram showing a configuration (a part) of an X-ray projection exposure apparatus (one example) according to the present embodiment.
The exposure apparatus shown in FIG. 1 receives an X-ray source 1, an illumination optical system 2 that irradiates a mask 3 with X-rays 20 generated from the X-ray source 1, a stage 4 of the mask 3, and an X-ray 22 from the mask 3. A projection imaging optical system 5 that projects and images a pattern formed on the mask 3 onto the wafer 6, a stage 7 of the wafer 6, and a filter 8.
[0026]
The wavelength of X-rays effective for imaging is 13 nm, and the projection imaging optical system 5 is a reduction optical system having an annular field of view.
As shown in FIG. 3, the filter 8 supports a Be (beryllium) thin film 8c having a thickness of about 1 μm by a metal support portion 8b having a thickness of 10 mm. The outer shape of the support part was a rectangle of 150 × 150 mm, which was larger than the mask 3.
[0027]
A portion of the filter 8 having a high X-ray transmittance (X-ray transmitting portion) 8a is a ring zone, and the size thereof is 5 mm in width and 120 mm in length, so that it is on the projection imaging optical system mask. Same as the effective field of view.
The filter 8 was arranged in parallel with the reflective surface 30 of the mask 3 so that the interval was about 1 mm. Further, the filter 8 is arranged so that the support portion 8b does not leave an optical path of X-rays effective for image formation.
[0028]
The filter 8 is formed by forming a thin film 8c of Be on the surface of the plate-like member, and then etching the portion of the plate-like member that becomes the optical path of the X-ray (the portion of the plate-like member facing the X-ray transmitting portion 8a). It was produced by removing the support portion 8b.
According to the X-ray projection exposure apparatus of the present embodiment, the filter 8 is provided close to the mask 3, so that dust adheres to the filter 8 even if dust floating in the space approaches the mask 3. Therefore, the filter 8 can prevent dust from adhering to the mask 3.
[0029]
Therefore, when the exposure was performed using the exposure apparatus of this example, no defects were observed in the formed resist pattern, and a desired resist pattern having a minimum size of 0.1 μm could be formed with a high yield.
The filter 8 had sufficient strength and was not damaged during exposure. Furthermore, since the support portion 8b has a sufficient thickness, it does not transmit X-rays, and the shape of the portion having a high X-ray transmittance (X-ray transmission portion 8a) is made into a ring shape, thereby forming a slit. Thus, a high-quality resist pattern was obtained.
[0030]
On the other hand, in the case of exposure using a conventional exposure apparatus that does not include the filter according to the present embodiment, many resist pattern defects occurred due to dust adhering to the mask. As a result, the yield deteriorated and the production capacity of the resist pattern was lowered.
[0031]
【The invention's effect】
As described above, according to the X-ray projection exposure apparatus of the present invention , it is possible to effectively prevent dust from adhering to the mask on which the pattern is formed. Thus, it is possible to effectively prevent a defect from occurring in the resist pattern formed.
[0032]
In addition, according to the X-ray projection exposure apparatus of the present invention , it is possible to give the filter the effect of a slit, and as a result, a high-quality resist pattern can be formed with a high yield.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration (a part) of an X-ray projection exposure apparatus according to an embodiment.
FIG. 2 is a block diagram showing a configuration (a part) of a mask and a filter in an X-ray projection exposure apparatus (one example) according to the present invention ((a) is a diagram showing a filter without a support part; b) is a view showing a filter provided with a support portion).
FIG. 3 is a view showing a filter in the X-ray projection exposure apparatus of the embodiment ((a) is a view showing a cross section of the filter, and (b) is a view showing a plane of the filter).
FIG. 4 is a block diagram showing a configuration (a part) of a conventional X-ray projection exposure apparatus.
FIG. 5 is a view showing a general reflection mask used in an X-ray projection exposure apparatus ((a) is a view showing a cross section of the reflection mask, and (b) is a dust attached to the reflection portion of the mask. It is a figure showing a state).
[Explanation of main part codes]
1. . . 1. X-ray source . . 2. Illumination optical system . . Mask 4. . . 4. Mask stage . . Imaging optical system6. . . Wafer 7. . . Wafer stage 8. . . Filter 8a. . . The part of the filter that has a high X-ray transmittance (for example, an annular X-ray transmission part)
8b. . . X-ray transmitting part supporting part 8c. Constituting the filter. . . Thin film layer or thin piece member 20, 21, 22, 23, made of a material having a high X-ray transmittance. . . X-ray 30. . . Reflective surface of mask 31. . . Mask substrate 32. . . X-ray reflective multilayer film 33. . . X-ray absorbing material layer (X-ray absorbing layer)
34. . . More than dust attached to the mask

Claims (4)

At least an X-ray source, an illumination optical system that irradiates a photomask arranged at a predetermined position with X-rays generated from the X-ray source, a stage of the photomask , and a filter provided close to the photomask When, X-rays, comprising: a projection imaging optical system for projection imaging a wafer disposed a pattern formed on the photomask in a predetermined position under the X-rays from the photomask, and a stage of the wafer In a projection exposure apparatus,
The X-ray projection exposure apparatus characterized in that the filter has a slit-shaped X-ray transmission part that transmits X-rays and a support part that supports the X-ray transmission part and does not transmit X-rays. 2. The X-ray projection exposure apparatus according to claim 1, wherein the projection imaging optical system has an annular field of view, and the X-ray transmission part has an annular shape . 3. An X-ray projection exposure apparatus according to claim 1 , wherein the shape and size of the X-ray transmission part are made equal to an effective field on a photomask of the projection imaging optical system . The X-ray transmitting portion, Be, Si, X-ray projection exposure apparatus according to claim 1 to 3, wherein the composed formed by Be compound, or a Si compound.

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