JPS61251033A - X-ray exposing device - Google Patents

Abstract

PURPOSE:To reduce the damage to be inflicted on the X-ray lead-out window and to make thinner the film of the window by a method wherein the direction of the normal of the X-ray lead-out window and the central axis of a group of electrodes to be used for growing plasma are mutually inclined, and at the same time, the central position of the X-ray lead-out window is deviated from the extension line of the axial direction of the plasma. CONSTITUTION:X-rays 8 are irradiated from high-temperature and high-density plasma 7 on the central axis of a group of an upper electrode 5 and a lower electrode 6; and ions, electrons, high-temperature gas and so forth, which are generated in the degradative process of the high-density plasma 7, are emitted in addition to the X-rays 8. The X-rays 8 are nearly radiated isotropically from each point of the plasma 7 on the periphery of a wafer 12, while to the X-rays, the ions, the electrons and the high-temperature gas and so forth are emitted to the axial direction of the plasma. In this case, when an X-ray lead-out window 10 is set up at a position with a constant angle from the axial direction of the plasma, the damage to be inflicted on the X-ray lead-out window by the particle groups 9 can be almost ignored. Meanwhile, in the X-ray exposure, an out-of-focussed image delta=2rs/D is generated according to the diameter 2r of the X-ray source, the gap (s) between the wafer 12 and a mask 11 and the distance D between the X-ray source and the mask 11. It is not desirable for the normal of the X-ray lead-out window to make an angle to exceed 45 deg. with the central axis of the electrodes because the out-of-focussed image becomes larger when the angle exceeds 45 deg.. The effective lower limit of the inclination angle is sufficient at 2-3 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an x&l exposure apparatus for fine pattern transfer for semiconductor integrated circuit manufacturing.

[Summary of disclosure]

The present invention provides an X-ray exposure apparatus using a plasma X-ray source, in which the normal direction of the X-ray extraction window and the central axis of a set of electrodes for generating plasma are tilted with respect to each other, and the center position of the X-ray extraction window is adjusted. By positioning it offset from the axial extension line of the generated plasma, it prevents damage to the X-ray extraction window due to particle groups from the plasma, and allows for high-efficiency extraction of X-rays and high-speed exposure by making the X-ray extraction window thinner. This paper discloses the technology of the X-ray exposure apparatus that has made this possible. Please note that this summary is provided solely for the purpose of quickly accessing the technical content of the present invention, and does not have any influence on the technical scope of the present invention or the interpretation of rights. .

[Conventional technology]

As the density of integrated circuits increases, fine and highly accurate transfer techniques are required, and one method is X-ray exposure. Conventionally, the X-ray sources for X-ray exposure equipment have been aluminum, copper,
An electron beam excitation method has been used in which metals such as molybdenum, silicon, and palladium are irradiated with electron beams to generate X-rays, but the X-ray generation efficiency is as low as 0.01%, and the X-ray source has a high output. There was a problem that productivity was low because there was no hope for improvement. In contrast, plasma X-ray sources are attracting attention because they have higher X-ray generation efficiency and can produce high-power X-rays. The plasma X-ray source uses capillary discharge and laser excitation.

There are plasma focus, gas injection type discharge, etc.

Gas injection type discharge is effective in terms of X-ray generation efficiency, output stability, etc.

Fig. 2 shows an example of a conventional gas injection discharge method, where l is a vacuum chamber, 2 is a vacuum pump, 3 is a gas reservoir for a high-speed opening/closing gas valve, 4 is a piston, 5 is an upper electrode having a gas injection passage, 6 7 is a lower electrode having a mesh shape or a hole, and 7 is a pinched plasma.

8 is the generated X-ray, 9 is the particle group, 10 is the X-ray extraction window, 1
1 is a mask, 12 is a wafer, and 13 is a capacitor.

14 is a discharge switch, 15 is a high-speed opening/closing gas valve, 18
17 is a gas mass; 18 is a conductive support that supports the lower electrode and forms a discharge space; and is connected to the capacitor 13 by a conductor 19.

To generate gas injection discharge, first open and close the gas valve 15 at high speed.
The piston 4 inside is driven at high speed, and the gas in the gas reservoir 3 is instantaneously injected between the discharge electrodes, and the electrodes 5 facing each other are placed in a vacuum.
A gas mass 17 is formed between the electrode 6 and the electrode 6. At the same time as a gas mass is formed between the electrodes, the switch 14 is closed, a voltage is applied between the electrodes by the charged capacitor 13, and the gas mass 1 is
7 is ionized to generate a cylindrical plasma. moreover,
The plasma is self-focused and compressed by the pressure of the magnetic field created by the current flowing along the central axis direction of the cylindrical plasma (hereinafter referred to as the plasma axis direction).

Generates high temperature, high density plasma. This high-density plug generates X-rays through the interaction of the ions and electrons inside.

In addition to X-rays, high-temperature, high-density plasma emits electromagnetic waves such as light, ions, electrons, high-temperature gases, etc., which can damage beryllium and other X-ray extraction windows. In particular, as shown in FIG. 2, when a gas mass 17 is turned into plasma and a plasma 7 is formed on the central axis of the electrode, a large amount of high-energy ion and electron particle groups 9 are generated in the axial direction of the plasma. radiated. Conventionally, in order to avoid the influence of this particle group, the radiation of one particle group in the plasma radial direction was 1/100 to 1/1,0 of the axial direction.
00, the X-ray extraction window 10, mask 11, wafer 12, etc. are installed in the radial direction of the pinched plasma 7 as shown in FIG. It is exposed to light. Figure 3 is x! This is the form of an X-ray source based on an X-ray pinhole photograph taken from the radial direction of the source where an Il mask is installed.

In such radial exposure, the gap between the mask and the sea urchin is 10 to 2
When proximity exposure was performed with 0ILm, the X-ray source shape was a long straight line, so the penumbra blur became large and fine batten transfer was impossible.

On the other hand, in plasma axial exposure, the diameter of the X-ray source is small and the penumbra blur is small, making it suitable for fine baton transfer. becomes larger. Therefore, it was necessary to limit the diameter of the X-ray extraction window and use thick extraction window material, which resulted in a small X-ray irradiation area and large X-ray attenuation, making it difficult to expose a large area for a short time. there were. .

[Interruption point where the invention attempts to solve the problem]

The present invention prevents penumbra blurring during extraction of X-rays in the plasma radial direction in a conventional X-ray exposure apparatus, prevents damage to the X-ray extraction window during plasma axial extraction, and prevents X! l
The aim is to enable high-speed exposure by making the extraction window thinner.

[Means for solving problems]

In the present invention, the normal direction of the X-ray extraction window and the central axis of a set of electrodes for generating plasma are tilted to each other, and
The above object is achieved by shifting the center position of the line extraction window from the axial extension line of the generated plasma.

[For production]

Particle groups that damage the X-ray extraction window material are emitted in the direction of the plasma center axis, and X-rays are emitted isotropically from the plasma, so the above method can guide only the X-rays to the X-ray extraction window. , damage to the X-ray extraction window can be prevented.

〔Example〕

Embodiment 1 FIG. 1 shows an embodiment of the present invention, in which 1 is a vacuum chamber, 2 is a vacuum pump for evacuating the vacuum chamber, 5 is an upper electrode, 6 is a lower electrode having a mesh shape or holes, and 7 is a vacuum pump for evacuating the vacuum chamber. pinch plasma,
8 is a generated X-ray, 11 is a mask, 12 is a wafer, 13 is a capacitor, 14 is a discharge switch, 15 is a high-speed opening/closing gas valve, 24 is a charging power source, 25 is a signal generator, 2B is a delay circuit, 27 is a high voltage pulse 28 is a power supply for driving a high-speed opening/closing gas valve; 28 is an insulator; 31 is an aligner; and 132 is an X-ray exposure pipe.

In order to operate this, the vacuum chamber 1 is evacuated to about 10-' to 10' Torr using the vacuum pump 2.
A discharge gas such as neon or krypton is introduced from the gas pump 30 to the high-speed opening/closing gas valve 15. Next, after charging the capacitor 13 with the charging power supply 24, the power supply 2 of the high-speed opening/closing gas valve 15 is activated by a signal from the signal generator 25.
8 to drive the piston 4 of the high-speed opening/closing gas valve 15 to form a gas mass 17 between the upper electrode 5 to which a high voltage is applied and the opposing lower electrode 6. At the same time, the signal from the signal generator 25 is output from the delay pulser 2B, which is set to coincide with the time when the discharge gas is injected between the electrodes 5 and 6.
is inputted to the high voltage pulse generator 27 through the high voltage pulse, and operates the discharge switch 14 with the high voltage pulse, applying a high voltage between the electrode 5 and the electrode 6 which are insulated by the insulator 28,
A discharge is caused by the gas mass 17. The gas is turned into plasma by electric discharge, and due to the interaction between the magnetic field created by the current flowing through the plasma and the ions and electrons in the plasma, it converges toward the center of the plasma, forming a high-temperature, high-density plasma on the central axis of the electrode, and X-rays 8 are irradiated. be done.

FIG. 4 is a detailed view of the discharge electrode section. 4 is a gas opening/closing piston, 5 is an upper electrode, 6 is a lower electrode, 16 is a ring-shaped gas injection passage, 17 is a gas mass injected from a high-speed opening/closing gas valve, 7 is a pinched plasma, and 8 is a generated X
Line 9 is a particle group.

In addition to X-rays 8, ions, electrons, and high-temperature gas generated during the collapse process of the high-density plasma are emitted from the plasma 7 pinched between the electrodes. While X-rays are emitted almost isotropically from each point of the plasma to the surroundings, ions, electrons, high temperature gas, etc. are emitted mainly in the plasma axis direction.

An aluminum foil was placed approximately 150 layers away from the lower electrode in the plasma axis direction, and damage to the aluminum foil caused by particles from the plasma was examined. As shown in Figure 5, the damage to the aluminum foil was as follows. The damage is concentrated in the center, and the damage rate rapidly decreases at 2 to 3c+s from the center. In this example, the X-ray extraction window is installed at a constant angle from the plasma axis direction. Because of this structure, damage caused by particles from the plasma can be almost ignored.

On the other hand, in X-ray exposure, as shown in Figure 6, the X-ray source diameter is 2r,
The wafer-mask spacing s, XdJ source-to-mask distance results in a penumbral blur δ=2rs/D. Further, as can be seen from FIG. 6, the X-ray source diameter becomes elliptical when viewed from the X-ray extraction window installed at a constant angle from the plasma axis direction, and the X-ray source diameter becomes large. However, in this example, the increase in the diameter of the X-ray source is approximately 2.5 times that of X-ray extraction in the axial direction of the plasma, about 5 times, but the intensity distribution of the X-rays becomes stronger in the center. Therefore, the actual diameter of the X-ray source is approximately 3 cm or less. Penumbral blur δ at this time
= 0.15 pm or less, which is not a large value compared to current equipment, and will not pose a problem as an X-ray exposure equipment for 0.51 Lm baton transfer.

If the angle between the normal line of the X-ray extraction window and the central axes of the upper and lower electrodes exceeds 45@, the disadvantage of radial exposure described above, that is, the penumbra blur will increase, which is undesirable.This is the lower limit of the effective tilt angle. varies depending on the configuration of the exposure equipment, but
In a normal device configuration, 2° to 3° is sufficient. Furthermore, in order to prevent uneven exposure and pattern deviation, it is natural to maintain a symmetrical relationship between the peripheral edge of the X-ray extraction window, the mask, and the wafer with respect to the X-ray source.

Embodiment 2 In Fig. 7, instead of tilting the X-ray source section, multiple X-ray extraction windows are installed in a direction with a certain tilt angle from the plasma axis.
The structure is such that a wafer and a mask are installed on the extension, 5 is the upper electrode, 6 is the lower electrode, 7 is the pinched plasma, 8 is the generated X-ray, 9 is the particle group, and 10 is the X-ray extraction window. , 11 is a mask, and 12 is a wafer. Since most of the particle group 9 generated from the pinched plasma 7 is concentrated in the plasma axis direction,
Compared to those with an X-ray extraction window,
The damage caused to zero is small, and it is possible to make the X-ray extraction window made of beryllium or the like thinner. Furthermore, since it has multiple X-ray extraction windows, it is possible to expose multiple wafers in one exposure.In this example, no holes are made in the plasma axis direction of the lower electrode, but of course Even if holes are made in the direction of the plasma axis, the effect remains the same.

In the embodiment shown in FIG. 7, if the normal lines of the X-ray extraction window, mask, and wafer are arranged parallel to the central axes of the upper and lower electrodes, the X-ray intensity varies depending on the position of the mask, resulting in uneven exposure. In addition, the X with respect to the mask is
Since the incident angles of the lines are different, a deviation occurs. It goes without saying that the window, mask, and wafer are each arranged so that their peripheral edges are symmetrical with respect to the X-ray source.

〔Effect of the invention〕

As explained above, by extracting X-rays at an angle to the plasma axis direction of the cylindrical plasma,
Damage to the X-ray extraction window due to ions, electrons, high-temperature gas, etc. generated from the plasma can be reduced, and a thin film X-ray extraction window can be used, while the distance to the X-ray source can be shortened. It has the advantage of being able to use wires with high efficiency.

Furthermore, throughput can be improved by high-efficiency X-ray extraction, and at the same time, since the diameter of the X-ray source is smaller than in radial extraction, submicron transfer is possible with proximity exposure.

Such an X-ray gradient extraction configuration can be applied to an X-ray analyzer, an X-ray microscope, a chemical reaction device using X-ray excitation, a film forming device using X-ray excitation, and an etching device using X-ray excitation. It can also be used to miniaturize these devices, promote reactions, etc.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention. Fig. 2 is a configuration diagram of a conventional plasma X-ray source, Fig. 3 is a diagram showing the form of a conventional plasma FIG. 6 is a diagram illustrating the state of damage caused by particle groups from plasma in the axial direction, FIG. 6 is a diagram illustrating penumbral blur δ in X-ray exposure, and FIG. 7 is a diagram illustrating another embodiment of the present invention. 1...Vacuum chamber, 2...Vacuum pump, 3...Gas reservoir. 4... Piston, 5... Upper electrode. 6... Lower electrode, 7... Pinched plasma, 8... Generated X-rays, 9... Particle group, 10... X-ray extraction window. 11...Mask, 12...Wafer. 13... Capacitor, 14... Discharge switch, 15... High speed opening/closing gas valve. 17... Gas mass, 24... Charging power source, 25... Signal generator, 2B... Delay pulser, 27... High voltage pulse generator, 28... High speed opening/closing gas valve driving power source, 28...
Insulator, 30...Gas cylinder. 31... Aligner-1 32... X-ray exposure pipe.

Claims (1)

[Claims] 1) In an X-ray exposure apparatus using a plasma X-ray source,
The normal direction of the X-ray extraction window and the central axis of the set of electrodes for plasma generation are tilted, and the center position of the X-ray extraction window is shifted from the axial extension line of the generated plasma. Characteristics of X-ray exposure equipment. 2) The X-ray exposure apparatus according to claim 1, characterized in that there is a plurality of X-ray extraction windows.