JPH0671465A - Eximer laser beam machine - Google Patents

Abstract

PURPOSE:To provide an eximer laser beam machine capable of reducing a size of focus through condensing eximer laser beam and machining a sub-micron pattern in short time and without mask. CONSTITUTION:A machine is composed of an eximer generator 12, which generates an eximer laser beam 6 with an unstable resonator 10, condensing lenses 16, which condenses the eximer laser beam into a focus 14 and a wave guide tube 18, which encloses in air tight a optical path between the eximer laser beam generator and condensing lenses and is filled with inert gas inside. Further, it is composed of stops 20a, 20b, 20c, which are arranged so as to stop down the eximer laser beam in the course of the wave guide or before and behind the condensing lenses, a moving table 22, which positions the working part of a object 7 to be machined on the focus of the eximer laser beam and a machining housing 24, which encloses the moving table in air tight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing apparatus using excimer laser light, and more particularly to a processing apparatus for focusing excimer laser light for fine processing.

[0002]

2. Description of the Related Art Excimer laser light is XeCl ^* , Kr
Short-wavelength ultraviolet light (200 to 300 n) generated when an excited molecule (excimer molecule) such as F ^* , ArF ^* (* indicates an excited state) returns from the excited state to the ground state.
m) and the photon energy is large (4 to 6e)
V) It has a feature. When the reaction gas is irradiated with this excimer laser light, photodissociation or photochemical reaction of the reaction gas molecules can be induced. Therefore, thin film formation by laser CVD through the photodissociation or photochemical reaction, surface layer modification such as laser doping, etc. It is being applied to fine processing such as laser etching.

In conventional fine processing using such excimer laser light, for example, etching processing, as shown in FIG. 4, an oxide film 2 (SiO ₂ ) and a polycrystalline silicon film 3 (Si) are formed on the surface of a silicon substrate 1. After being formed, chlorine gas 4 (Cl ₂ ) of halogen molecules is made to flow as a reaction gas for etching, and excimer laser light 6 is irradiated through the mask 5, and the excimer laser light 6 that has passed through the mask 5 is a polycrystalline silicon film. Cl ⁻ (chlorine ion) was formed on the surface layer of No. 3, and this ion reacted with Si to become SiCl _{4 and} vaporized to etch the polycrystalline silicon film 3.

[0004]

The excimer laser light is
Although it has a high output, it has a drawback that directivity, coherence, and monochromaticity are inferior to those of other laser beams. For this reason, the conventional processing apparatus using a mask has a problem that the excimer laser light passing through the mask cannot be made into a perfect parallel light and it is difficult to process a submicron pattern having a line width of 1 μm or less.

Further, in the conventional processing apparatus, since the excimer laser light is expanded and only the light passing through the mask is irradiated to the work piece, the intensity of the excimer laser light on the work surface of the work piece is weak and the processing time is long. There was such a problem. Further, since a mask is indispensable in the conventional processing apparatus, there is a problem that it cannot be applied to free processing without a mask, for example, fine processing such as etching, film formation and ablation in repairing a circuit pattern.

The present invention was devised to solve such problems. That is, an object of the present invention is to provide an excimer laser processing apparatus capable of processing a submicron pattern of 1 μm or less in a short time without using a mask.

[0007]

According to the present invention, an excimer laser generator having an unstable resonator for generating excimer laser light, a condenser lens group for concentrating the excimer laser light at a focal point, and A waveguide that hermetically surrounds the optical path between the excimer laser generator and the condenser lens group, and is filled with an inert gas inside, and in the middle of the waveguide and before and after the condenser lens group. An aperture stop attached so as to narrow the light flux of the excimer laser light, a moving table for positioning a processed portion of the workpiece at the focal point of the excimer laser light, and a processing housing that hermetically surrounds the moving table. A featured excimer laser processing apparatus is provided.

According to an embodiment of the present invention, the length of the waveguide is set so that the distance from the entrance of the excimer laser light to the focal point of the condenser lens group is at least 2 m. preferable. Further, it is preferable that the waveguide includes a horizontal portion and a vertical portion, and that a mirror that refracts the excimer laser light at a right angle is attached to a position where the horizontal portion and the vertical portion intersect. Furthermore, it is preferable that the moving table further includes a heater for heating the workpiece.

[0009]

As described above, the excimer laser light has the drawback of being inferior in directivity, coherence, and monochromaticity. For this reason, the optical system in the conventional processing apparatus cannot produce perfect parallel light. Therefore, even if the excimer laser light is condensed using a lens, the size of the focal point cannot be reduced to 1 μm or less, and a submicron pattern of 1 μm or less cannot be processed.

The present invention uses an excimer laser generator having an unstable resonator to generate excimer laser light, thereby generating excimer laser light with relatively good directivity aligned on the optical axis. Since the excimer laser light is guided to the condenser lens group through the waveguide in which the inert gas is sealed, there is little attenuation of the excimer laser light, and it is mounted in the middle of the waveguide so as to narrow the light flux of the excimer laser light. The directivity of the excimer laser light is improved because it has a stop, and the stop attached before and after the condenser lens group to narrow the luminous flux of the excimer laser light greatly reduces the influence of aberration of the condenser lens group. It is a small one.

That is, the present invention improves the drawbacks of the excimer laser light by using a plurality of means in combination, and as a result, improves the directivity of the excimer laser light and reduces the aberration of the condenser lens. By reducing the influence, the size of the focal point can be reduced to 1 μm or less, and a submicron pattern having a line width of 1 μm or less can be processed in a short time without using a mask.

Further, according to the structure of the present invention, since the moving table for positioning the processing portion of the workpiece at the focal point of the excimer laser beam and the processing housing which hermetically surrounds the moving table are provided, the processing housing is provided in the processing housing. An appropriate reaction gas (for example, etching gas) is introduced, the inside pressure is set to an optimum pressure and temperature, and a work piece, for example, a substrate of an integrated circuit can be finely processed. Therefore, it is possible to perform free processing without a mask, for example, fine processing such as etching, film formation, and ablation in repairing a circuit pattern.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of an excimer laser processing apparatus according to the present invention, and FIG. 2 is a sectional view of a processing housing. In FIG. 1, an excimer laser processing apparatus according to the present invention includes an excimer laser generator 12 having an unstable resonator 10 for generating an excimer laser beam 6 and a condenser lens group for converging the excimer laser beam 6 at a focal point 14. 16, a waveguide 18 that hermetically surrounds the optical path between the excimer laser generator 12 and the condenser lens group 16 and is sealed with an inert gas, and the middle of the waveguide 18 and the condenser lens. Stops 20a, 20b, 20c mounted to narrow the luminous flux of the excimer laser light 6 before and after the group 16, a moving table 22 for positioning the processed portion of the workpiece 7 at the focal point 14 of the excimer laser light, and a moving table. A processing housing 24 that hermetically surrounds 22.

The unstable resonator 10 is composed of, for example, two opposed convex mirrors 10a and 10b as shown in the figure, and the laser light reciprocates between the two mirrors like a normal resonator so that the laser light is emitted. However, since the mirror surface is convex, the laser light at a position away from the optical axis is scattered outside the resonator, and only the thin light very close to the optical axis is amplified by the unstable resonator 10. It is radiated. The unstable resonator 10 may have a structure other than the illustrated one, for example, one using a concave mirror. Further, the excimer laser generator 12 is
XeCl ^* , KrF ^* , ArF ^* , or any other excimer molecule is used to generate ultraviolet light having a short wavelength, and the excitation method may be electron beam excitation, discharge excitation, or any other method. .

As shown in the figure, the waveguide 18 is an elongated horizontal portion 18 into which the excimer laser light 6 is horizontally introduced from the left end.
a, a vertical portion 18b that is connected to the right end of the horizontal portion 18a and extends upward, a horizontal portion 18c that is connected to the upper end of the vertical portion 18b and extends horizontally, and is connected to the right end of the horizontal portion 18c and the lower end is a condenser lens. The vertical portion 18d is connected to the group 16. Further, a plane mirror 19 is obliquely attached at a position where the horizontal portions 18a and 18c and the vertical portions 18b and 18d intersect each other so that the excimer laser light 6 is refracted at a right angle.
With such a configuration, the excimer laser light 6 introduced horizontally can be vertically irradiated to the workpiece 7 via the condenser lens group 16.

The length of the waveguide 18 depends on the excimer laser light 6
The distance from the entrance to the focal point 14 by the condenser lens group 16 is set to be at least 2 m, preferably 5 m. Further, as shown in the figure, a diaphragm 20a for narrowing the luminous flux of the excimer laser light 6 is provided in the middle of the waveguide 18, for example, near the left end of the horizontal portion 18a. The diaphragm 20a preferably has, for example, a rectangular opening (aperture). A plurality of diaphragms 20a may be provided in the middle of the waveguide 18. With such a configuration, the excimer laser light 6 having a relatively high directivity from the excimer laser generator 12 having the unstable resonator 10 can be further narrowed down, and the excimer laser light 6 reaching the condenser lens group 16 can be focused on the optical axis. All the above,
It can be highly directional.

The inert gas sealed in the waveguide 18 is, for example, Ar (argon), He (helium), N ₂
(Nitrogen), and when ArF ^* is used, Ar or He is particularly preferable. Thereby, the attenuation of the excimer laser light can be minimized. Further, economically, the operating cost can be reduced by using N ₂ . The inert gas may be enclosed in the waveguide 18 or may be circulated.

As shown in FIG. 2, the processing housing 24 has a window 24a through which the excimer laser light 6 passes, and the excimer laser light 6 is introduced through the window 24a. A gas supply pipe 25 having a gas nozzle (not shown) is provided inside the processing housing 24. A reaction gas necessary for processing is introduced from the gas supply pipe 25, and an exhaust device (not shown) is used from a gas exhaust port 24b. It is designed to exhaust gas. The reaction gas is, for example, chlorine gas (Cl
₂ ) is used as a reaction gas for etching. Further, the inside of the processed housing 24 can be held in a vacuum.

The movable table 22 is mounted inside the processing housing 24. The moving table 22 is
It can be used in a vacuum or in a reaction gas, and the workpiece 7 can be moved two-dimensionally in the horizontal direction by a driving device (not shown). Furthermore, it is preferable that it can move in the vertical direction. With this configuration, the processed portion of the workpiece 7 can be positioned at the focal point 14 of the excimer laser light. The moving table 22 further includes the workpiece 7
A heater 26 for heating the With this configuration, the temperature of the workpiece 7 can be optimally set for machining.

FIG. 3 is a block diagram of the condenser lens group 16.
In this figure, the condenser lens group 16 is composed of a beam expander 16 a that expands the luminous flux of the excimer laser light 6 and a condenser lens 16 b that collects the expanded excimer laser light 6 at the focal point 14. In the illustrated example, the beam expander 16a is composed of a combination of a concave lens and a convex lens, and the condenser lens 16b is a single convex lens, but the present invention is not limited to this, and for example, the condenser lens 1
6b may be a combination lens.

Further, in FIG. 3, diaphragms 20b and 20c are provided in front of and behind the condenser lens group 16, specifically above the beam expander 16a and below the condenser lens 16b so as to narrow the light flux of the excimer laser light 6. Installed. The diaphragms 20b and 20c have, for example, rectangular openings (apertures). Each opening size is 5m
It is m square and 3 mm square. The number of diaphragms is not limited to two as shown in the figure, and may be three or more, or may be one. Further, it may be provided not in front of and behind the condenser lens group but in the middle thereof, for example, below the beam expander 16a.
With this configuration, the excimer laser light 6 that has passed near the optical axis of the condenser lens 16c can be condensed, and the influence of lens aberration can be made extremely small.

As described above, according to the present invention, the excimer laser light 6 generated by using the excimer laser generator 12 having the unstable resonator 10 is aligned on the optical axis and has a relatively good directivity. Since the laser light 6 is generated and further guided to the focusing lens group 16 through the waveguide 18 in which the inert gas is sealed, the excimer laser light 6 is less attenuated and the waveguide 18 Since the diaphragm 20a attached so as to narrow the light flux of the excimer laser light 6 is provided on the way, the directivity of the excimer laser light 6 is improved, and the light flux of the excimer laser light 6 is further narrowed before and after the condenser lens group 16. Attached diaphragm 20
Since b and 20c are provided, the influence of the aberration of the condenser lens group 16 is made extremely small.

That is, the present invention improves the drawbacks of the excimer laser light by using a plurality of means in combination, and as a result, improves the directivity of the excimer laser light and reduces the aberration of the condenser lens. By reducing the influence, the size of the focal point can be reduced to 1 μm or less, and a submicron pattern having a line width of 1 μm or less can be processed in a short time without using a mask.

Further, according to the structure of the present invention, since the moving table for positioning the processing portion of the workpiece at the focal point of the excimer laser light and the processing housing which hermetically surrounds the moving table are provided, the processing housing is provided in the processing housing. An appropriate reaction gas (for example, etching gas) is introduced, the inside pressure is set to an optimum pressure and temperature, and a workpiece, for example, an integrated circuit substrate can be finely processed. Therefore, it is possible to perform free processing without a mask, for example, fine processing such as etching, film formation, and ablation in repairing a circuit pattern.

[0025]

Therefore, according to the present invention, the size of the focal point can be reduced to 1 μm or less by condensing the excimer laser light, and a submicron pattern having a line width of 1 μm or less can be formed in a short time without a mask. It has the effect that it can be processed with.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an excimer laser processing apparatus according to the present invention.

FIG. 2 is a sectional view of a processed housing.

FIG. 3 is a configuration diagram of a condenser lens system.

FIG. 4 is a schematic explanatory diagram of conventional fine processing using excimer laser light.

[Explanation of symbols]

 1 Silicon Substrate 2 Oxide Film 3 Polycrystalline Silicon Film 4 Chlorine Gas 5 Mask 6 Excimer Laser Light 7 Workpiece 10 Unstable Resonator 12 Excimer Laser Generator 14 Focus 16 Focusing Lens Group 16a Beam Expander 16b Focusing Lens 18 Conductor Wave tube 18a, 18c Horizontal part 18b, 18d Vertical part 19 Mirror 20a, 20b, 20c Aperture 22 Moving table 24 Processing housing 24a Window 25 Gas supply pipe 26 Heater

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B23K 26/12 7425-4E H01S 3/225

Claims (4)

[Claims] 1. An excimer laser generator having an unstable resonator for generating excimer laser light, a condenser lens group for converging the excimer laser light at a focal point, the excimer laser generator and the condenser lens group. A waveguide that hermetically surrounds the optical path between the inside and the inside, and is installed so as to narrow the luminous flux of the excimer laser light in the middle of the waveguide and before and after the condenser lens group. An excimer laser processing apparatus comprising: a diaphragm, a movable table that positions a processed portion of a workpiece at a focal point of the excimer laser light, and a processing housing that hermetically surrounds the movable table. 2. The length of the waveguide is set so that the distance from the entrance of the excimer laser light to the focal point of the condenser lens group is at least 2 m. Excimer laser processing device described. 3. The waveguide comprises a horizontal part and a vertical part, and a mirror for refracting excimer laser light at a right angle is attached at a position where the horizontal part and the vertical part intersect.
The excimer laser processing apparatus according to claim 1, wherein 4. The excimer laser processing apparatus according to claim 1, wherein the moving table further includes a heater for heating the workpiece.