JP2001058899A - Method and apparatus for processing metal body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a great number of spherical projections made of a metal semi-regularly arranged on the surface of the metal by irradiating the metal installed in a fixed vacuum atmosphere with a pulse laser beam. SOLUTION: A metal body 32 is preferably a single crystal of a low-melting metal such as W32, etc., W32 as the metal body 32 is held by a retaining holder 33 in a vacuum chamber 22. The vacuum chamber 22 is evacuated, a He gas is introduced from an inert gas inlet pipe 31 and the pressure in the vacuum chamber 22 is retained, for example, at 4kPa. Then a pulse laser beam L is oscillated at 1-1.2 j/P output at 8-10 ns pulse width at 1-20 Hz number of pulse repetition from Nd:YAG laser oscillator 23 of 1,064 nm wavelength, rotates a plane of polarization in a (λ/2) plate 24, condensed through refraction mirrors 25 and 27 by a condensing lens 28 to form a focus through an introduction window 29 on a W surface 32a. W fine projections are formed on the W surface 32a at 0-30 deg. irradiation angle at 300-1,200 times of number of irradiations.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for processing a metal body, and more particularly, to a method of irradiating a pulsed laser to a metal body to form a large number of hemispherical minute projections on the surface of the metal body. The present invention relates to a body processing method and a body processing apparatus.

[0002]

2. Description of the Related Art Hitherto, various studies have been conducted to form ripple (striped) minute projections on a substrate surface by laser irradiation. For example, PM at Stanford University
Fauchet, AESiegman et al., Appl.Phys. Lett., 40
According to (1982), 824, a linearly polarized Nd: YAG laser beam is irradiated onto Si, Ge, GaAs, or the like, and ripples with stripes perpendicular to the polarization direction are formed. The University of Toronto
Jeff.F.Young, JESipe, JSPreston, HM van Dri
According to el et al.'s paper, `` Appl.Phys.Lett., 41 (1982), 261 '', Ge, Al, Si, etc. were irradiated with linearly polarized Nd: YAG laser light, and again perpendicular to the polarization direction. The formation of ripples in which streaks are arranged is observed, and when the irradiation angle is 45 degrees or more, they are arranged in parallel to the polarization direction. According to the paper `` Laser Research, 26 (1998), 155 '' by Akira Yabe and Hiroyuki Shinno of the National Institute of Materials Technology, polymers are irradiated with laser beams such as XeCl, KrF, and ArF to form protrusions. A microstructure is formed and its shape is changed depending on the type of polarized light. However, there is no report that a large number of particles (ultrafine particles) are formed on the substrate surface.

[0003]

DISCLOSURE OF THE INVENTION The present invention is based on a new finding not found in the prior art, and is intended to form regularly arranged hemispherical microprojections having a uniform size on the surface of a metal body. An object of the present invention is to provide a method and an apparatus for processing a metal body that can be performed.

[0004]

The above object is achieved by irradiating a metal body provided in a predetermined reduced-pressure atmosphere with a pulse laser beam to form a hemispherical projection made of the metal on the surface of the metal body. A metal body processing method characterized by forming a large number
Solved by

Alternatively, a metal body provided in the decompression chamber, an introduction window made of a transparent material for closing an opening formed in a wall of the decompression chamber, and a pulse laser oscillator provided outside the decompression chamber. Irradiating a laser beam oscillated from the pulsed laser oscillator onto the metal body surface in the decompression chamber from the introduction window to form a large number of hemispherical projections made of the metal on the metal body surface. And a metal body processing apparatus characterized in that:

[0006]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a W projection forming apparatus 21 according to the present embodiment.

[0008] In the decompression chamber 22, a tungsten (W) 32 as a metal body is provided and held by a holding holder 33. W32 has, for example, a diameter of 9 mm and a thickness of 3
It has a circular block shape of mm (it may be a square with similar dimensions) and is made of single crystal, and the crystal orientation of the surface 32a is oriented to (100).

The decompression chamber 22 is connected at its lower part to a vacuum exhaust system (not shown) via a valve 26. Also,
In the upper part, an inert gas introduction pipe 31 is connected, and a valve 30 is connected.
Via an inert gas, for example He.

An opening 22a is formed in the side wall of the decompression chamber 22 facing the surface 32a of W32.
A laser light introducing window 29 made of a transparent material, for example, quartz, is attached to block a.

An Nd: YAG pulse laser oscillator 23 (output: 0.5 to 1.2 J / P, wavelength: 1064 nm) is provided outside the decompression chamber 22. The laser light L oscillated from the Nd: YAG laser oscillator 23 is introduced through a (λ / 2) plate 24, refraction mirrors 25 and 27, and a condenser lens 28 which are also provided outside the decompression chamber 22. 2
9, the light is focused on the W surface 32 a and irradiated.

Next, formation of a W projection by the above-described apparatus 21 will be described.

First, the inside of the decompression chamber 22 is 6.7 in the evacuation system.
The pressure is reduced to a pressure of × 10 ⁻⁴ Pa (5 × 10 ⁻⁶ Torr) or less. Thereafter, He gas is introduced from the inert gas introduction pipe 31 and the pressure in the decompression chamber 22 is increased to, for example, 4 while performing differential evacuation.
It is kept at kPa (30 Torr).

In such an atmosphere condition,
The pulse laser light L is oscillated from the Nd: YAG laser oscillator 23. The oscillation conditions are as follows: output 1 to 1.2 J /
P, pulse width 8-10 ns, pulse repetition number 1-20
Hz. The oscillated laser light L has its polarization plane rotated by a (λ / 2) plate 24, is condensed by a condenser lens 28 via refraction mirrors 25 and 27, passes through an introduction window 29, and passes through a W surface. The light is focused and irradiated on 32a. The irradiation angle is 0 ° to 30 ° (the direction perpendicularly irradiated on the W surface 32a is 0 °). Irradiation frequency 300 to 1200
The irradiation is completed at the same time.

Next, the W32 subjected to the above-described processing is taken out and observed with a scanning electron microscope (SEM).
As shown in FIG. 2, a large number of W microprojections 35 regularly arranged at a constant pitch in a ring shape are observed around a keloid-shaped laser irradiation mark 36. FIG. 3 is an enlarged perspective view of a portion A in FIG. The W microprojections 35 have a uniform particle size, each having a diameter of about 700 nm and a height of about 30 nm.
It is a single-crystal microprojection having a substantially hemispherical shape of 0 nm and oriented in the crystal orientation (100). The spacing between the adjacent protrusions 35 in the circumferential direction is 300 to 400 nm, and the pitch in the radial direction is 1000 nm (1 μm), which is regularly arranged.

As described above, in the present embodiment, extremely small protrusions in units of nm can be formed. For example, a spacer for maintaining a constant distance between the rotating body and the substrate or a spacer made of double glass If it is applied to, for example, it is effective in maintaining a minute space. Further, W has a property of easily emitting electrons. For example, W on which a projection is formed is used as a cathode of an electron gun used in a large-sized display and the like, and application to this is also possible. It is possible. This embodiment can be easily manufactured at low cost.

Although the embodiments of the present invention have been described above, the present invention is, of course, not limited thereto, and various modifications can be made based on the technical concept of the present invention.

In the above embodiment, the atmosphere in the decompression chamber 22 is such that an inert gas is introduced under reduced pressure. However, it is not always necessary to introduce an inert gas.

The size of the projections is not limited to that described in the embodiment, and fine projections having a uniform particle diameter of 100 nm to 1 μm can be formed by changing the oscillation conditions of the pulse laser.

Further, in the above embodiment, W made of a single crystal is used, but it is not necessary to use a single crystal. However, when a non-single crystal is used, cracks are likely to occur by laser irradiation, and the formed protrusions do not show regular orientation. Further, a metal other than W, particularly a high melting point metal such as Ta or Mo may be used. When a high-melting-point metal is used, only its surface melts and flows to form desired microprojections. However, with a low-melting-point metal (for example, copper), the desired microprojections do not stop at only the surface. Is difficult to form. However, even with a low-melting-point metal, by cooling with liquid nitrogen or the like, only the surface can be melted and flown, and the same minute projections as those obtained when a high-melting-point metal is used can be obtained.

[0021]

As described above, according to the present invention, it is possible to form a large number of hemispherical fine projections having a uniform particle size on a metal body surface by regularly arranging them at a constant pitch.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an apparatus for processing a metal body according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view partially broken around a laser irradiation mark on a W surface formed by the apparatus of FIG. 1;

FIG. 3 is an enlarged perspective view of a portion A in FIG. 2;

[Explanation of symbols]

 22 decompression chamber 23 pulse laser oscillator 29 introduction window 31 inert gas introduction pipe 32 metal body

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4E068 AH00 CJ01 CJ09 DB01 4G077 AA02 BA01 FH08

Claims (9)

[Claims] 1. A metal body is disposed in a predetermined reduced-pressure atmosphere,
A method for processing a metal body, comprising irradiating the metal body with a pulsed laser beam to form a large number of hemispherical projections made of the metal on the surface of the metal body. 2. The method according to claim 1, wherein the metal is a single crystal. 3. The method according to claim 1, wherein the metal is a high melting point metal. 4. The method according to claim 3, wherein the high melting point metal is tungsten. 5. The pulse laser has a wavelength of 1064n.
5. The method for processing a metal body according to claim 1, wherein the metal is a Nd: YAG laser. 6. The method according to claim 1, wherein the predetermined reduced-pressure atmosphere is an inert gas atmosphere. 7. A metal body provided in the decompression chamber, and an introduction window made of a transparent material for closing an opening formed in a wall of the decompression chamber.
A pulsed laser oscillator disposed outside the decompression chamber, and irradiating the surface of the metal body in the decompression chamber with the laser light oscillated from the pulsed laser oscillator from the introduction window to the surface of the metal body. An apparatus for processing a metal body, wherein a large number of hemispherical projections made of the metal are formed. 8. The pulse laser oscillator has a wavelength of 10.
The apparatus according to claim 7, wherein the apparatus is a 64 nm Nd: YAG laser oscillator. 9. The apparatus for processing a metal body according to claim 7, wherein the decompression chamber is in an inert gas atmosphere.