Electric heating – Metal heating – By arc
Reexamination Certificate
1999-01-21
2001-01-30
Evans, Geoffrey S. (Department: 1725)
Electric heating
Metal heating
By arc
Reexamination Certificate
active
06180915
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a laser machining method and a laser machining apparatus, and more particularly to a laser machining method and a laser machining apparatus by which a fine pattern can be formed on a material at high speed.
2. Description of the Related Art
A variety of materials have been heretofore worked in accordance with wet etching method wherein various chemical solutions are used, or laser ablation method wherein various types of laser are used.
However, it has been known that among a variety of materials, for example, quartz glass has an absorption edge of light of around 170 nm, besides bond energy between constituent atoms is also remarkable, so that it is difficult to form a fine pattern on a material at high speed in accordance with such a conventional machining method as described above.
More specifically, when quartz glass is worked up according to wet etching method wherein a chemical solution such as acid is used, a speed in working is fast, but there has been a problem of poor controllability for working profile and working speed of the quartz glass, so that the method is not suitable for fine working.
Furthermore, although reactive ion etching method (RIE) is a machining method suitable for effecting precisely fine working of quartz glass, there has been a problem of slow working speed (It is known to be a working speed of 1 nm/s or less in case of working SiO2).
Moreover, there has been such a problem that another lithographic step using a resist is necessary for effecting fine pattern working in wet etching method wherein the above described chemical solution such as acid is employed or reactive ion etching method, so that the whole steps for working treatment become complicated, resulting in a reason of requiring a long period of time.
On the other hand, there is laser ablation method as a method for pattern-working a material at high speed without employing a resist, but it is necessary that a wavelength of laser beam applied in laser ablation method has a high absorption coefficient with respect to a material to be worked. For this reason, when quartz glass is intended to work in accordance with laser ablation method, it is required to use laser beam having a wavelength of 170 nm or less. In this connection, however, there has been such a problem that a laser applicable for working of quartz glass is not substantially present with taking costs for photon, and output thereof into consideration.
OBJECT AND SUMMARY OF THE INVENTION
The present invention has been made in view of a variety of the problems as described above involved in the prior art. Accordingly, an object of the present invention is to provide a laser machining method and a laser machining apparatus by which a fine pattern can be formed at high speed with respect to a material such as quartz glass which exhibits a short wavelength at absorption edge of light and has high bond energy between constituent atoms.
In order to achieve the above described object, a fine pattern is formed on a material to be worked in accordance with ablation with the use of transparent laser beam exhibiting no absorption with respect to the material to be worked and without employing any resist in the present invention.
Thus, according to the present invention, a variety of materials can be worked by means of a laser producing laser beam having a wavelength extending over visible region, ultraviolet region, and infrared region.
More specifically, a laser machining method according to the present invention, comprises the steps of irradiating transparent laser beam with respect to a material to be worked; producing plasma simultaneously with the above described irradiation at a place close to an objective surface of the material to be worked; and generating ablation on the objective surface of the material to be worked by means of interactions of the above described plasma with the laser beam irradiated upon the material to be worked, thereby to work the above described material.
Furthermore, a laser machining method according to the present invention, comprises the steps of irradiating transparent laser beam with respect to a material to be worked through a mask having a predetermined pattern; producing plasma simultaneously with the above described irradiation at a place close to an objective surface of the material to be worked; and generating ablation corresponding to the predetermined pattern of the above described mask on the objective surface of the material to be worked by means of interactions of the above described plasma with the laser beam irradiated upon the material to be worked through the mask, thereby to work the above described material.
Moreover, a laser machining apparatus according to the present invention, comprises a material to be worked having an objective surface to be worked by means of laser; a target opposed to the objective surface of the material to be worked; and a laser for irradiating transparent laser beam with respect to said material to be worked and at the same time, irradiating the transparent laser beam upon the above described target to produce plasma from the target between the aforesaid target and the objective surface of the above described material to be worked; ablation being generated on the objective surface of the material to be worked by means of interactions between the plasma produced from the target and laser beam irradiated upon the material to be worked from the laser, thereby to work the material.
Still further, a laser machining apparatus according to the present invention, comprises a material to be worked having an objective surface by means of laser; a target opposed to the objective surface of the material to be worked; a laser for irradiating laser beam upon the material to be worked to perform working thereof; and a second laser for irradiating laser beam upon the above described target to produce plasma from the target between the aforesaid target and the objective surface of the material to be worked; ablation being generated on the objective surface of the material to be worked by means of interactions between the plasma produced from the target and laser beam irradiated upon the above described material to be worked from the laser, thereby to work the above described material.
Yet further, a laser machining apparatus according to the present invention, comprises a material to be worked having an objective surface by means of laser; a laser for irradiating laser beam upon the material to be worked to perform working thereof; and a plasma producing means for producing plasma at a place close to the objective surface of the above described material to be worked; ablation being generated on the objective surface of the material to be worked by means of interactions between the plasma produced from the above described plasma producing means and laser beam irradiated upon the material to be worked from the laser, thereby to work the above described material.
Moreover, a laser machining apparatus according to the present invention, comprises further a mask having a predetermined pattern and disposed between the above described laser and the above described material to be worked; the laser irradiating laser beam upon the above described material to be worked through the mask; and ablation corresponding to the predetermined pattern of the mask being generated on the objective surface of the material to be worked by means of interactions between the plasma produced from the plasma producing means and laser beam irradiated upon the material to be worked from the laser through the mask, thereby to work the above described material.
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patent: 5987920 (1999-11-01), Bosman et al.
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Midorikawa Katsumi
Sugioka Koji
Zhang Jie
Del Valle Marguerite
Evans Geoffrey S.
The Institute For Physical And Chemical Research
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