JPS6068538A - X-ray generator - Google Patents

Abstract

PURPOSE:To enable homogeneous stable irradiation of X-rays to be performed over a wide area by installing a variable-field-producing variable electromagnet which scans the electronic orbit in vertical direction with respect to time. CONSTITUTION:A variable electromagnet (diode) 11 used to change the optical path and having a lateral field component (Hh) is installed in the immediate back of a lateral-focusing tetraode electromagnet 9. At this point, an electron flux longitudinally focused with a longitudinal-focusing tetrode electromagnet 10 is slightly shifted in longitudinal direction by the lateral field component of the variable electromagnet 11. This shift is then amplified with the lateral focusing tetrode electromagnet 9 (for lateral focusing and longitudinal divergence) thereby greatly shifting the orbital surface of electrons traveling in a deflecting diode electromagnet 8 is vertical direction (Y direction). Consequently, synchrotron radiation (soft X-ray) 2 traveling over a wafer 4 moves in vertical direction.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray generator used for soft X-ray phosphorography using synchrotron radiation.

2. Description of the Related Art Conventionally, in the production of LSI elements having fine structures, photolithography technology has been used to transfer patterns onto resist films.

However, due to the phenomenon of light diffraction, the pattern width that can be transferred is limited to about 1 μm, which is about the same as the original wavelength.

In order to further advance miniaturization, phosphorography technology that can be used for mass transfer of submicron patterns is needed, and one of these is X-ray phosphorography technology that has little diffraction effect.

Conventionally, characteristic X-rays obtained by irradiating a solid target with an electron beam have been used as an X-ray source, but since the wavelength thereof is less than IOA, there are the following problems.

That is, since all materials have high transmittance for X-rays in this wavelength range, the absorption efficiency into the resist is low, the exposure time becomes long, and the absorber film becomes too thick to obtain sufficient mask contrast. Also, because the wavelength is short,
The energy of photoelectrons generated in the resist film or substrate is high, and secondary photoelectrons are diffused, resulting in low resolution. moreover,
To avoid penumbra blur and geometric distortion effects,
It is necessary to maintain a sufficient distance between the radiation source and the wafer, but since this moderate X-ray source is a diverging source, increasing the distance between the wafers will reduce the efficiency of beam use, resulting in insufficient beam intensity. Obtaining this requires a very powerful X-ray source, which is currently technically difficult.

Synchroton synchrotron radiation (soft X-rays) is attracting attention as a technique for resolving the above-mentioned problems. As shown in Figure 1 (al), synchrotone synchrotron radiation 2 is an electromagnetic wave emitted by electrons e when their orbits are bent by a magnetic field H. Its spread is conical and concentrated in the direction of movement of electrons e. Since the electron e moves on the electron orbit 1, as shown in Fig. 1 (
In the case of the normally used static magnetic field Hg in the vertical direction as shown in b), due to the superposition of the light emitting points on the electron orbit 1,
The angle distribution is uniform in the horizontal direction (inward the raceway plane) and narrows and diverges in the vertical direction (perpendicular to the raceway plane).Therefore, there is no wasted beam dissipation, and all beams are distributed on the Uninor surface. It can be concentrated on the top and used for exposure.

Furthermore, the synchrotron radiation light 2 has a continuous spectrum ranging from X-rays to microwaves as shown in Fig. 2.
By choosing the kinetic energy of the electron e, the short wavelength
IOs or 1 suitable for phosphorography with few line components
) It is possible to obtain a 100A beam with soft X-rays as the main component.

In addition, orbit radius ratio = 2 m, current I: 100
mA.

FIG. 2 shows a case where the distance between the light emitting point and the sea urchin is 1=lQ7yL, and the elevation angle from the orbital plane is θ=-Orad.

As described above, the synchrotron radiation 20 intensity that can be used for exposure on the eight faces of the sea urchin is very strong, and pattern transfer is possible in a short exposure time.

In order to take advantage of its strength, it is desirable to shorten the distance between the light emitting point and the sea urchin/% within a range that does not cause penumbra blur or geometric distortion, and it is necessary to keep the distance between 5 and 10 meters. be. However, in this case, the spread angle in the vertical direction is very narrow as mentioned above, and on the contrary, it is too narrow to expose one chip of LSI. For example, when the distance between the light emitting point and the sea urchin is 1OrrL, the intensity of the soft X-ray component effective for phosphorography becomes almost uniform at 4■
There is a range of degrees. This expansion can hardly be increased even if the energy or orbital radius of the electron e is changed. Therefore, in order to achieve a uniform exposure area with a width of about 1cIrL to 1OcrrL in the vertical direction, which is necessary to expose a C, T chip or l wafer, K changes the optical path of the soft X-rays in some way. I need to do it.

Several devices shown in FIGS. 3(a) to 3(d) below have been proposed for this optical path change.

In FIG. 3, 1 is an electron orbit, 2 is a synchrotron radiation beam, 3 is a mask, 4 is a wafer to be exposed, 5 is a plane mirror, 6 is a convex mirror or a concave mirror, and T is a plane mirror or a concave mirror. Hereinafter, FIGS. 3(a) to 3(d) will be explained in order. (1) Apparatus for vertically moving the wafer 4 itself (see FIG. 3 (al)).

(2) A device that uses a plane mirror 5 to reflect synchrotron radiation 2 and vibrates the plane mirror 5 at an appropriate speed to oscillate the radiation in the vertical direction (see Fig. 3 (bl)).

(3) A device that reflects synchrotron radiation 2 using a convex or concave mirror 6 to obtain uniform intensity over a wide area (see Figure 3<G)).

(4) Combining several plane mirrors or concave mirrors 7,
A device that reflects unnecessary emitted light on the left and right sides of the wafer 4 and increases uniform spread in the vertical direction (see FIG. 3(d)).

Among these, (1) is a wafer aligner that has a complicated mechanism for accurately positioning a number of masks 3 one after another on a wafer 4 and processing a large number of wafers 4, and a moving mechanism. This requires one more degree of freedom, which is expected to pose technical difficulties in practical use.

(21, (3), and (4) all use mirrors 5 and 6, but in this case, the effective soft X-ray spectral intensity depends first on the reflectance of the lunar surface of the mirror. This makes it difficult to predict the exposure time.Secondly, the reflectance gradually decreases due to the adsorption of impurities caused by light irradiation, which requires maintenance work such as replacing the mirror. The intensity of soft X-rays must be checked.Furthermore, the deterioration does not necessarily proceed uniformly on the mirror surface, and there is a risk that uneven exposure will occur.

The present invention proposes an X-ray generator having an optical path changing device that does not have the drawbacks of the conventional optical path changing device as described above. The practical side of this invention will be explained below with reference to the drawings.

One of the devices for generating synchrotron radiation 2 is a deuteron storage ring, which will be explained by taking this as an example.

The electron storage ring deflects the electron flux.

If we consider only the focusing system, for example, as shown in FIG. Four positive pole electromagnets 9 for horizontal focusing and 4M pole electromagnets 10 for vertical focusing are used to stably circulate the electron flux.

Here, a variable electromagnet (two poles) 11 having 4Ei field components Hh in the lateral direction for changing the optical path was inserted immediately after the 4 positive electrode electromagnet 9 for lateral focusing.

At this time, the direction of the electron flux vertically focused by the four positive electrode electromagnets 9 for horizontal focusing is slightly shifted in the vertical direction due to the horizontal magnetic field component of the variable electromagnet 11. This deviation is amplified by the four positive electrode electromagnets 9 for horizontal focusing (converging in the horizontal direction but diverging in the vertical direction), and the orbital plane of the electrons in the two polar electromagnets 8 for deflection is in the vertical direction (
This results in a large shift in the Y direction). Therefore, the synchrotron radiation light (soft X-rays) 2 on the wafer 4 moves in the vertical direction.

For example, when a current IA is passed through the variable electromagnet 11, a transverse magnetic field of about 50 Gauss is generated, which causes the orbital plane of the electron e to change and move 13 fins to a position on the sample ion away from the light emitting point. By oscillating this current value with a triangular wave as shown in Fig. 5 at a constant speed (for example, 0.3 sec), it is possible to uniformly expose the Ueno 4 in a vertical width range of 3 cIn. 〇According to the above method, since there is no optical element between the X-ray emission point and the sea urchin...4, it is possible to obtain highly uniform synchrotron radiation. Second, synchrotron radiation has a gentle continuous spectrum, making it easy to predict the required exposure time, and third, it is possible to always obtain the same amount of soft X-rays with a constant electron current. Therefore, the exposure time can be easily controlled.

In the above embodiment, the variable electromagnet 11 was installed immediately after the four positive electrode electromagnets 10 for longitudinal focusing, but it may be installed anywhere as long as it has a variable transverse magnetic field component.

As described in detail above, the present invention provides a variable electromagnet for generating a variable magnetic field that temporally scans the electron trajectory in the vertical direction. Uniformly, making the most of
Stable, high-throughput soft-X birch phosphorography becomes possible.

[Brief explanation of drawings]

Figure 1 (a) is a schematic diagram showing the distribution of synchrotron radiation emitted by electrons in a magnetic field at a certain moment, and Figure 1 (b) is a synchrotron radiation emitted by electrons moving in a vertical static magnetic field. Figure 2 is a schematic diagram showing the distribution of synchrotron radiation. Figure 2 is a characteristic diagram showing the distribution of the intensity of radiation emitted from the electron multiplication device with respect to wavelength. FIG. 4 is a schematic diagram of an X-ray generator that shows an embodiment of the present invention, and FIG. It is a waveform diagram showing an example of a current flowing through an electromagnet. In the figure, 1 is an electron orbit, 2 is a synchrotron radiation beam, 3 is a mask, 4 is a sea urchin/'%, 5 is a plane mirror, 6 is a convex mirror or a concave mirror, 1 is a plane mirror or a concave mirror, 8 is a dipole electromagnet for deflection, 9 is a quadruple-pole electromagnet for horizontal focusing, 10 is a four-positive electromagnet for vertical focusing, 11 Fig. 1 (a) (b) Fig. 2

Claims (1)

[Claims] In an X-ray generation device that uses soft X-rays of synchrotron radiation to transfer patterns on a resist film, a variable electromagnet for generating a variable magnetic field is provided that temporally moves the electron trajectory that generates the synchrotron radiation in the vertical direction. An X-ray generator characterized in that: