JPH03212927A - Exposure equipment for X-ray lithography - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an exposure apparatus for X-ray lithography, and is particularly effective for forming precise and fine patterns such as patterns for high-density semiconductor integrated circuits. The present invention relates to an exposure apparatus for X-ray lithography.

(Prior Art) Generally, a semiconductor integrated circuit is manufactured by forming a plurality of patterns on a semiconductor wafer and then dividing the semiconductor wafer into a plurality of chips. Currently, an optical reduction projection exposure method is mainly used for pattern formation. Even with this light reduction projection exposure method, the resolution has been improved by improving the performance of the lens and shortening the wavelength of the light source, making it possible to form fine patterns. However, in this optical reduction projection exposure method, the line width is 0, which is desired for high-density semiconductor integrated circuits.
, 5 μm or less is difficult to form, and other exposure methods are considered necessary.

One of these methods is the X-ray exposure method, among which 5OR (S
ynchrotron 0rbltal Radlat
An X-ray exposure method using a lon) ring as an X-ray source is seen as promising.

An exposure apparatus for X-ray lithography using this SOR ring as an X-ray source has an exposure section that supports a semiconductor wafer and a mask on which a pattern is formed to be printed on a semiconductor wafer in a predetermined positional relationship. A high vacuum beam line that guides the X-rays emitted from the SOR ring, an X-ray mirror that cuts the short wavelength portion of the X-rays emitted from the SOR ring,
It consists of a Be window that supports a Be film placed between the exposure section and the beam line. Normally, this Be window forms a partition wall between an ultra-high vacuum of a beam line and an exposure section installed in an atmosphere of atmospheric pressure or a partially low vacuum.

Incidentally, the X-rays emitted from the SOR ring have a uniform irradiation width in the horizontal direction, but have a Gaussian intensity distribution in the vertical direction, and the irradiation width is narrow.

Therefore, as an X-ray source, this SOR ring can secure a relatively wide exposure area in the horizontal direction, but only a narrow exposure area in the vertical direction.

On the other hand, in the manufacture of semiconductor integrated circuits, 20 to 30 m
Since an exposure area of approximately m square is required, when the SOR ring is used as an X-ray source, a means is required to expand the irradiation area of the emitted X-rays. The means for enlarging it are: (a) Swinging the trajectory of the electron beam inside the SOR ring (c) Swinging the X-ray mirror that cuts the short wavelength part of the X-rays emitted from the SOR ring (c) There are methods such as fixing the line and scanning the mask and semiconductor wafer together.

On the other hand, with respect to Be films, particularly those manufactured by rolling, the amount of X-ray transmission changes due to uneven film thickness, resulting in uneven exposure. Therefore, as a countermeasure to this problem, it has been reported that exposure unevenness can be reduced by mechanically shaking the Be film.

(Proceedings of the 36th Applied Physics Association Conference p. 61
0) However, if the orbit of the electron beam is oscillated in order to expand the irradiation area of X-rays as described above, the same SOR
This method is not practical because it is necessary to consider the influence on X-rays emitted from the ring to other beam lines and changes in the accumulated current life.

In addition, when the X-rays are scanned by swinging the mirror, the incident angle of the X-rays on the mirror changes, the reflectance changes accordingly, and the X-ray intensity in the scanning direction on the mask and semiconductor wafer changes. This impairs the uniformity of exposure. To prevent this, for example, J, Vac, S
ci, Tecnol, B6 (6) NOV/DEC, 19
88, p2128. : Precisely Con
trolledOscillating Mirror
5ysteIlf'or Hlghly Unif'
o-Wm Exposure in 5syncrotr
As described in Radlatlon on Radlatlon, it is necessary to control the swinging speed of the mirror depending on its swinging angle.

In addition, the means for scanning the mask and semiconductor wafer together is
In the scanning direction, it is expected that the influence of unevenness in film thickness can be averaged out to some extent. However, if crystal anisotropy occurs in the Be film due to its processing, exposure unevenness cannot be sufficiently reduced by means of swinging the X-ray mirror.

(Problems to be Solved by the Invention) As mentioned above, the line width desired for high-density semiconductor integrated circuits is 0.
．． An exposure apparatus for X-ray lithography using an SOR ring as an X-ray source is considered to be promising for forming patterns of 5 μm or less. However, in this exposure apparatus for X-ray lithography, SO
The X-rays emitted from the R ring have a uniform irradiation width in the horizontal direction, but have a Gaussian intensity distribution in the vertical direction, and the irradiation width is narrow. Therefore, although a wide exposure area can be secured in the horizontal direction, only a narrow exposure area can be obtained in the vertical direction. On the other hand, in the manufacture of semiconductor integrated circuits, an exposure area of about 20 to 30 angles is required, so when using an SOR ring as an X-ray source, the emitted
A means to expand the irradiation area of the line is required. As a means of enlarging it, (a) Swinging the orbit of the electron beam inside the SOR ring (b) Swinging the X-ray mirror that cuts the short wavelength part of the X-rays emitted from the SOR ring (c) Swinging the X-rays There are methods such as fixing the electron beam and scanning the mask and semiconductor wafer together, but in (a) the method of swinging the trajectory of the electron beam, the electron beam is emitted from the same SOR ring to other beam lines. It is not practical because it is necessary to consider the influence on X-rays and changes in the accumulated current life. Also, (b)
In the method of scanning X-rays by swinging a mirror, the reflectance changes as the angle of incidence of the X-rays on the mirror changes, and the X-ray intensity in the scanning direction on the mask and semiconductor wafer fluctuates. Exposure uniformity is impaired. In order to prevent this, it is necessary to control the swinging speed of the mirror according to the swinging angle of the mirror. In addition, with the method (c) of moving the mask and semiconductor wafer together, it is expected that the effect of uneven film thickness can be averaged out to some extent in the direction of movement, but the processing of the Be film may cause crystal anisotropy. If this occurs, there are problems such as the inability to sufficiently reduce exposure unevenness with this method.

This invention was made in view of the above problems, and
In X-ray lithography exposure equipment that uses a device that emits directional X-rays, such as an SOR ring, as an X-ray source, a sufficient exposure area can be secured, and exposure due to uneven Be film thickness can be achieved. The purpose is to sufficiently reduce unevenness.

[Structure of the Invention] (Means for Solving the Problems) In an exposure apparatus for X-ray lithography, the exposure apparatus has an irradiation width in a second direction perpendicular to the first direction with respect to an irradiation width in a first direction. an X-ray source that emits a wide range of X-rays; an exposure section that supports an exposed object on which a photoresist film is formed and a mask on which a pattern is formed to be printed on the photoresist film in a predetermined positional relationship; a drive device that moves the supported exposed object and the mask in the first direction; a high vacuum beam line that guides the X-rays emitted from the X-ray source to the exposure section; a Be window movably attached to the exposure section and the beam line, supporting a Be film disposed between the exposure section and the beam line along the path of the X-rays; and a rocking device for rocking in the second direction at a speed faster than the moving speed of the exposed object and the mask.

(Function) As described above, by swinging the Be window in the second direction, the unevenness in the film thickness of the Be film supported by the Be window in the second direction can be averaged, and the exposure unevenness in the second direction can be averaged. can be reduced. Furthermore, when the exposed object and the mask are moved in the first direction that is orthogonal to the second direction, since this moving direction is orthogonal to the direction in which the X-ray irradiation width is wide, the apparent It is possible to expand the light area and at the same time provide B to the exposed object.
The X-rays passing through each point of the E film contribute equally, and it is possible to reduce the exposure unevenness caused by the unevenness of the film thickness of the Be film in the first direction. Therefore, two-dimensionally uniform exposure is possible, and even if crystal anisotropy occurs in the Be film due to processing, for example, exposure unevenness can be sufficiently reduced.

(Example) Hereinafter, the present invention will be described based on an example with reference to the drawings.

FIG. 1 shows the configuration of essential parts of an exposure apparatus for X-ray lithography for printing a pattern on a semiconductor wafer, which is one embodiment of the present invention. This exposure apparatus uses an SOR ring (2) as an X-ray source that emits X-rays (1) with a wide irradiation width in the horizontal direction (second direction) perpendicular to the irradiation width in the vertical direction (first direction). The X-rays (1) emitted from this SOR ring (2)
A cylindrical beam line (
3) is located. Inside this beam line (3), X-rays (1
An X-ray mirror (4) is arranged to cut off the short wavelength portion of the beam and reflect the other portion.

Reflected X-rays (la) reflected by this X-ray mirror (4)
), a semiconductor wafer (W) and a mask (M) on which a predetermined pattern is formed to be printed on the photoresist film formed on this semiconductor wafer (W) are supported with a certain minute distance between them. An exposure section (5) is arranged. The semiconductor wafer (W) and the mask (M) are supported by the exposure section (5) so that they are spaced a certain distance apart and are irradiated with the reflected X-rays (2a) vertically. This exposure part (5) is
The beam line (3) is maintained at ultra-high vacuum, whereas the beam line (3) is maintained at atmospheric pressure or a partially reduced pressure state of low vacuum. As shown by the arrow (6) in FIG. A drive device (7) consisting of a motor, a cam, etc. that moves at a constant speed in a vertical direction perpendicular to the irradiation width direction) is disposed.

Furthermore, a Be window (lO) supporting the Be film (9) is arranged between the beam line (3) and the exposure section (5). This Be window (10) forms a partition wall that maintains the beam line (3) at an ultra-high vacuum with respect to an exposure section (5) that is maintained at atmospheric pressure or a reduced pressure state of a partially low vacuum. is attached with bellows (lla) and (llb), and is movably attached to each of the beam line (3) and the exposure section (5) via the bellows (lla) and (flb). And the rocking device (1
2) The above semiconductor wafer (ν) and mask (M)
At a speed faster than the moving speed of
As shown in 3), the semiconductor wafer (W) and the mask (M) are configured to swing in the horizontal direction perpendicular to the moving direction.

By the way, when the exposure apparatus is configured as described above, even if the Be film (9) has uneven thickness in the horizontal direction, the Be window (1
0), it is possible to average out the unevenness of the film thickness in the horizontal direction, and it is possible to reduce the unevenness of exposure in the horizontal direction on the semiconductor wafer (W). Also,
When the semiconductor wafer (W) and mask (M) are moved as one in the vertical direction, the X radiated from the SOR ring (2)
The exposure area in the narrow direction of the irradiation width of line (1) is apparently expanded upward.

At the same time, as shown in Figure 3, the X-rays (la) passing through each point (A) to (E) on the Be film (9) begin to contribute equally to the semiconductor Ueno (if). , Be film (9
) even if there is unevenness in film thickness in the vertical direction, the exposure unevenness caused by the unevenness in film thickness can be reduced.

Therefore, according to the exposure apparatus configured as described above, it is possible to perform two-dimensionally uniform X-ray exposure on the semiconductor wafer (ν).
Even if crystal anisotropy depending on the processing method occurs, this Be
Exposure unevenness due to the film (9) can be sufficiently reduced,
A desired pattern can be printed on the semiconductor U/1(w).

In the above embodiment, the case was described in which the semiconductor wafer and the mask were moved once in the vertical direction, but the vertical movement of the semiconductor wafer and the mask is shown in FIG. 3 by the solid line followed by the broken line (■5 ) The reciprocating motion may be made as shown in (), or the reciprocating motion may be repeated.

[Effects of the Invention] The exposure apparatus for X-ray lithography can be used with
an X-ray source that emits radiation, an exposure section that supports an exposed object on which a photoresist film is formed and a mask on which a pattern is formed to be printed on the photoresist film in a predetermined positional relationship; a drive device that moves the exposed light body and the mask together in the first direction; a high vacuum beam line that guides the X-rays emitted from the X-ray source to the exposure section; The Be window is movably attached to the exposure section and the beam line, and supports the Be film disposed between the exposure section and the beam line along the path of the X-rays. a swinging device that swings the Be window in the second direction at a speed faster than the moving speed of the exposed object and the mask; When the Be film is moved in a first direction perpendicular to the second direction, unevenness in the film thickness of the Be film supported by the Be window in the second direction can be averaged by the rocking of the Be window. Exposure unevenness can be reduced. In addition, due to the movement of the exposed object and the mask, since the direction of movement is perpendicular to the direction in which the X-ray irradiation width is wide, at the same time the exposure area is expanded, each part of the Be film is X-rays passing through the points can be made to contribute equally, and exposure unevenness caused by unevenness in the thickness of the Be film in the first direction can be reduced.

Therefore, it is possible to perform two-dimensional uniform exposure on the exposed object, and even if crystal anisotropy occurs due to processing in the Be film, exposure unevenness due to this can be sufficiently reduced, and The desired pattern can be printed onto the photoresist film on the body.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the main part of an exposure apparatus for X-ray lithography, which is an embodiment of the present invention, and FIG. FIG. 3, a diagram showing the relationship, is a diagram for explaining the effect of moving the semiconductor wafer and mask.

Claims (1)

[Claims] A second direction perpendicular to the first direction with respect to the irradiation width in the first direction.
an X-ray source that emits X-rays with a wide directional irradiation width; an exposure unit that supports an exposed object on which a photoresist film is formed and a mask on which a pattern is formed to be printed on the photoresist film in a predetermined positional relationship; , a drive device that moves the exposed object and the mask supported by the exposure section together in the first direction; a high vacuum beam line that guides X-rays emitted from the X-ray source to the exposure section; The Be film is movably attached to the exposure section and the beam line and supports a Be film disposed between the exposure section and the beam line along the path of the X-rays emitted from the X-ray source. An exposure apparatus for X-ray lithography, comprising: a Be window; and a swinging device that swings the Be window in the second direction at a speed faster than the moving speed of the exposed object and the mask.