JPH08318390A - Ablation debris removing device - Google Patents

Abstract

PURPOSE: To highly speedily and efficiently remove debris by providing a vacuum suction device having a suction nozzle at a position facing to a ablation machining part, sucking the debris generated caused on the ablation and removing them. CONSTITUTION: A vacuum suction device is provided at a position facing an ablation machining part which is irradiated with an excimer laser beam, it is installed near the machining range of an object to be machined and it is positioned at a position so that the raising velocity of a plume is minified and the debris A is sucked with a suction nozzle 1. The opening shape of the suction nozzle 1 is made suitably in the form of a cylinder, an ellipse, a rectangle or a slit, etc. Therefore, the excimer laser beam equipment without sticking the debris on the front face of the object to be machined or without reducing the energy of the following laser pulse is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ablation debris removing device for removing debris generated in ablation processing in which a workpiece is precisely processed in a non-contact manner by utilizing the ablation phenomenon of excimer laser light.

[0002]

2. Description of the Related Art As a non-contact precision processing method, a processing method utilizing an ablation phenomenon of excimer laser light is known.

Conventionally, the ablation process using the excimer laser light has been mainly applied to the field of micromachining, but debris, which is a processed product generated by ablation, is used for cleaning the processed object after processing,
Alternatively, depending on the processing material, it is reduced by processing in an inert atmosphere such as helium or by processing in an oxygen atmosphere.

[0004]

However, it is difficult to completely remove the debris generated by ablation in the above conventional technique. In particular, it is difficult to remove the debris redeposited on the workpiece.

Further, the form of debris varies from a gaseous form to several μm depending on the type of material and the intensity of incident energy.
The particles are distributed in a wide range of particles up to a size, and various methods must be considered depending on the shape of the debris that is washed after processing.

Further, in processing in a helium atmosphere, since the ejection speed of the ablation plume (explosion cloud) is faster than that in air, debris is dispersed far away, and apparently debris is reduced. appear. This is considered to be a result of the generated debris being oxidized and turned into a gas in an oxygen atmosphere.

The above-mentioned processing in an atmosphere of helium or oxygen is effective only in processing relatively limited materials, and is not effective in processing all materials.

Further, an essential point to be considered is that when the oscillation frequency of the excimer laser is increased in order to perform high-speed processing, the plume generated by the preceding excimer laser pulse is still in the optical path of the excimer laser. Since the ablation by the subsequent excimer laser is performed in the existing state, there is a problem that the excimer laser for the subsequent ablation causes energy loss.

For these reasons, removing the plume generated by ablation at high speed has become a more important issue than simply removing debris.

An object of the present invention is to solve the above-mentioned problems of the prior art at the same time, and for all the materials to be ablated and the incident energy of excimer laser light, the ablation process is performed in real time. The purpose is to provide a device for removing debris.

[0011]

In order to achieve the above object, the present invention is used by being attached to an ablation processing apparatus (developing machine, peeling machine, micromachining processing machine, etc.) by excimer laser light by the following means. The debris generated by ablation is removed by suctioning with an exhaust system.

(Means 1) A single or a plurality of tubular nozzles, or an annular suction nozzle surrounding a region processed by excimer light is set and used at a position on the workpiece where the plume velocity is slower than the suction flow velocity.

(Means 2) An entrance window made of a quartz material or the like that transmits excimer laser light, a bottom plate having an opening facing the entrance window and close to a processing region of a workpiece, and an exhaust connected to an exhaust system. The nozzle structure includes a mouth, a space between the entrance window and the bottom plate, and a nozzle formed between the exhaust port.

That is, the first invention according to claim 1 is provided with a vacuum suction device at a position facing the ablation processing portion for irradiating the excimer laser light, and debris generated by the ablation is removed by suction. It is characterized by

According to a second aspect of the present invention, the vacuum suction device according to the first aspect has at least one tubular nozzle, and the plume velocity due to the ablation is slower than the flow velocity of the vacuum suction. It is characterized in that it is installed at a position on the workpiece.

Further, the third invention according to claim 3 is
The vacuum suction device according to the first aspect of the present invention has an annular suction nozzle surrounding the ablation processing portion, and is installed at a position on the workpiece where the speed of the plume due to the ablation is slower than the flow speed of the vacuum suction. Characterize.

The fourth invention according to claim 4 is
The vacuum suction device in the first invention has an entrance window made of a quartz material that transmits excimer laser light, and an exit port that is wider than the area of the ablation processed portion of the workpiece by at least 2 mm and faces the entrance window. The flow velocity at the portion deviated from the optical path of the excimer laser port between the bottom plate, the exhaust port connected to the exhaust system, the space between the entrance window and the bottom plate, and the exhaust port is 25 m / s or more. A nozzle-like structure is provided, and the bottom plate is installed at a distance of about 1 mm or less from the workpiece.

[0018]

[Function] Ablation by irradiation of excimer laser light is defined as a phenomenon in which when a material is irradiated with ultraviolet excimer laser light having a high energy density, the material exposed to the laser light is photolyzed and scattered. .

Therefore, by utilizing this ablation phenomenon, for example, by using a certain pattern as a mask, illuminating this with an excimer laser beam, and forming an image on the surface of the workpiece, the shape as the above mask pattern is obtained. It will be formed on the surface of the surface-treated product.

With laser light having a wavelength of visible light or longer, decomposition of a substance by irradiation with laser light occurs mainly by a thermal process (thermal decomposition), but when excimer laser light is used, especially for many organic substances. Is decomposed by a non-thermal process that directly breaks chemical bonds, and is currently used mainly in the field of ultraprecision machining such as micromachining.

In practice, the processing technique utilizing the ablation phenomenon of excimer laser light can be applied not only to the field of micromachining described above, but also to the thin film forming process in the manufacture of TFTs and the like, so that ablation can be performed. Ablation development that can perform the process of exposure and development using conventional photolithography technology at the same time by selecting a suitable reegist material.
Similarly, application to ablation peeling is also considered.

The ablation phenomenon is understood to be a kind of explosive phenomenon because excimer laser light with a pulse width of 20 to 30 ns photolyzes a substance with a high energy density.

FIG. 6 is an explanatory view of the ablation phenomenon, which schematically shows a shadow graph of the ablation phenomenon by a dye laser (pulse width of about 5 ns) delay-synchronized with the pulse of the excimer laser light, and 15a to 15f are excimer laser light. Shape of the behavior of debris caused by the irradiation of the beam, 16 and 16 'are shock waves, 1
Reference numeral 7 indicates a workpiece.

The figure shows a novolac resin with 248 nm and 1
This is a case where irradiation with an excimer laser beam of 00 mJ / cm ² is applied.

First, when the surface of the work piece 17 is irradiated with the excimer laser light, as shown in (a), the debris is released from the irradiation area of the work piece 17 with the excimer laser light. Occurs.

The shock wave 16 is formed by debris consisting of the released gas or light fine particles.

The front speed of the shock wave 16 is 1.5 at a delay time of 0.2 to 0.4 μs or less.
It is a supersonic velocity of about km / s, which is 1 μs in (b).
After that, a shock wave with normal sound velocity level 1
6 '.

A high pressure is applied to the inside of the wave front of the shock wave, whereby relatively heavy particles, which are the main constituent of the debris 15b, are suppressed.
After about 10 μs, the debris 15c started to rise because the internal pressure suddenly decreased, and the debris 15c started to rise to 20 μs in (d).
Mushroom cloud-like plume 15d called so-called plume after s position
Is observed.

The plume 15d is formed like 15e of (e) and 15f of (f) with the passage of time.

The rising speed and height of this plume in air are 20 m / s and about 3 mm, respectively, at the delay time of 100 μs under the above conditions. When the incident energy density is 300 mJ / cm ² , the ablation rate is about 3 times, but the plume height and rising speed are about 1.5 times at most.

The above-mentioned behavior of the ablation phenomenon slightly differs depending on the material to be processed, and there is a change such that a clear cloudy cloud-like plume is not observed. Especially, the quantitative value naturally changes depending on the material. Is 300 mJ /
It is one guideline of cm ² or less.

That is, in the above-mentioned first invention, by providing a vacuum suction device for sucking and removing the debris generated by the ablation at a position facing the ablation processing portion for irradiating the excimer laser beam, the workpiece is processed. The debris does not adhere to the surface of the laser and does not reduce the energy of the subsequent laser pulse.

Further, in the above-mentioned second invention, the vacuum suction device of the first invention has at least one tubular nozzle, and is located at a position on the workpiece where the velocity of the plume due to the ablation becomes slower than the flow velocity of the vacuum suction. The debris is efficiently removed by installing the.

Further, in the third invention, there is provided an annular suction nozzle surrounding an ablation portion, and the first invention is located at a position on the workpiece where the speed of the plume caused by the ablation is slower than the flow speed of vacuum suction. By installing the vacuum suction device, the debris can be removed more efficiently.

In the fourth aspect of the invention, the vacuum suction device of the first aspect of the invention has an entrance window made of a quartz material that transmits excimer laser light and a region that is approximately 2 mm or more wider than the area of the ablation portion of the workpiece. And a bottom plate having an emission port facing the incident window and an exhaust port connected to an exhaust system, and an optical path of the excimer laser port between the exhaust port and the space between the incident window and the bottom plate. It is assumed that the bottom plate is provided with a nozzle-like structure having a flow velocity of 25 m / s or more at a portion deviated from
The debris can be removed more efficiently by installing the debris with the following intervals.

[0036]

Embodiments of the ablation debris removing device according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic diagram for explaining the structure of a first embodiment of the ablation debris removing device according to the present invention, in which 1 is a suction nozzle, 2 is an exhaust unit communicating with a vacuum pump (not shown), and 3c is a suction buffer. Space, 6 is a workpiece.

This embodiment has a structure having one suction nozzle 1 which is the basic structure of the present invention, and is installed at a position close to the processing region of the workpiece and the plume rising speed is sufficiently small. Then, the debris A is sucked as indicated by the arrow.

The opening shape of the suction nozzle is cylindrical, elliptical,
A rectangular shape, a slit shape, or the like may be appropriately selected depending on the material of the workpiece, the configuration of the excimer laser light processing apparatus, the energy used, and the like.

According to the present embodiment, it is possible to provide an excimer laser processing apparatus in which the debris does not adhere to the surface of the workpiece and the energy of the subsequent laser pulse is not reduced.

The efficiency of suction can be improved by installing a plurality of the above-mentioned structures around the processing area.

FIG. 2 is a schematic view for explaining the configuration of the second embodiment of the ablation debris removing device according to the present invention, and the same reference numerals as those in FIG. 1 correspond to the same functional parts.

In this embodiment, the suction nozzle 1 has a slit-like annular shape that is opened so as to encircle and surround the processing region of the workpiece. It is desirable that the respective suction buffer spaces 3a be communicated with each other, and the exhaust part 2 may be provided at one place.

According to the present embodiment, it is possible to provide an excimer laser processing apparatus in which the effect of removing debris is improved, the debris does not adhere to the surface of the workpiece, and the energy of the subsequent laser pulse is not reduced.

FIG. 3 is a schematic view for explaining the structure of a third embodiment of the ablation debris removing device according to the present invention. 3a and 3b are side walls forming a suction container, 4 is an entrance window for excimer laser light, and 5 is an entrance window. Is the bottom plate that constitutes the suction container,
Reference numeral 5a denotes an opening for laser light irradiation, and the same reference numerals as those in FIG. 1 correspond to the same functional portions.

The figure shows that debris suction can be performed more efficiently,
Further, in order to completely remove the plume, the suction container structure is formed so as to enclose the suction region in a substantially sealed manner.

That is, in the present embodiment, the suction container is constituted by the entrance window 3 for the excimer laser light, the bottom 4 having the opening for irradiating the workpiece 6 with the laser light, and the side walls 3a, 3b. The suction buffer space 3a communicates with each other, and the exhaust unit 2 may be provided at one place.

It is desirable to make the opening 5a of the bottom plate 5 as small as possible, but it is necessary to prevent the movement of the shockwave front during ablation so that it is necessary.
It is preferable that the opening be widened by about 2 mm from each edge of the processing region of the workpiece 6. The side walls 3a and 3b are also shaped so as not to interfere with the irradiation of laser light.

It is important that the entrance window 4 is made of a material that allows excimer laser light to pass therethrough, for example, a quartz plate, and its installation height is set higher than the reach distance of the shock wave front.

Further, the bottom plate 5 can be made as close as possible to the workpiece 6 to be ablated, and the overall area can be made large to further improve the suction efficiency.

It is considered that this is because the pressure in the suction container becomes low and the speed of the shockwave front increases. However, in suction, it is necessary to consider the flow velocity and streamline that do not cause local fluctuation of the refractive index due to gas disturbance in the optical path of the excimer laser light.

FIG. 4 is a schematic view for explaining the structure of the fourth embodiment of the ablation debris removing device according to the present invention, showing a more specific structure for attaching to the ablation processing device, in which the suction buffer space 3c is in communication. Then, the exhaust unit 2 is connected to the exhaust unit 2, 13 is an ablation debris removing device, and the same reference numerals as those in FIG.

In the figure, the height of the suction container 3 is 65 m.
The bottom plate 5 of the suction container 3 is set on the surface of the workpiece with a gap of 1 mm.

The excimer laser light enters through the entrance window 4 and is applied to the workpiece through the opening 5a of the bottom plate 5.

The debris A generated by ablation reaches the exhaust unit 2 from the suction buffer space 3c through the suction nozzle 1 as shown by the arrow, and is exhausted by a vacuum pump (not shown).

As a result of ablation processing of the novolac resin by the ablation processing device using the ablation debris removing device of this structure, the laser oscillation frequency of 2 kHz is about 1.5 times as high as that without the suction container. Was able to obtain the ablation rate of. Further, the debris could be completely removed except for a minute portion on the edge of the laser irradiation part.

With this configuration, it can be easily installed in the processing portion of the ablation processing device,
It is possible to remove the generated debris and perform high quality processing.

FIG. 5 is an explanatory view of a structural example in which the ablation debris removing device shown in FIG. 4 is attached to an ablation processing device and applied to the processing of a color filter substrate which constitutes a liquid crystal display element. A color filter substrate which is a work, 7 is a color filter layer, 7a is an unnecessary convex portion formed on the color filter layer, 8 is a moving table on the color filter substrate 6 ', 9 is an excimer laser,
Is an excimer laser beam, 11 is a uniformized illumination optical system, 12
Is an irradiation laser beam, 14 is a dielectric multilayer mask, and 18 is an image forming optical system.

In the figure, an excimer laser 9 oscillates a laser beam 10 having a wavelength of 248 nm, and a homogenizing illumination optical system 11 including an integrator is used to form the convex portion 7a on the surface of the color filter layer 7 of the color filter substrate 6 '. Illumination of a 2 × 50 mm ² slit-shaped mask pattern is performed on the excimer dielectric multilayer film mask 14 having an opening covering the removal region.

This mask pattern is imaged on the surface of the color filter layer 7 by the 1: 1 imaging optical system 18. The working distance of the imaging lens was 70 mm, and the ablation debris removing device 131 mm was installed between the working distance and the suction container having a height of 65 mm as shown in FIG.

For debris suction, a dry vacuum pump having an exhaust capacity of 60 l / min is used. The incident energy density of the excimer laser light is 300 mJ / cm ² .

By the ablation processing apparatus having the above-described structure, unnecessary convex portions 7a formed on the color filter layer of the color filter substrate are removed and flattened, and debris generated by the processing remains on the color filter layer. It was possible to obtain a high quality color filter substrate.

[0063]

As described above, according to the present invention,
Debris generated during ablation processing using high-speed excimer laser light that oscillates at a high repetition frequency can be removed at high speed and with high efficiency.
Achieves faster processing and cleaner processing.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating the configuration of a first embodiment of an ablation debris removing device according to the present invention.

FIG. 2 is a schematic diagram illustrating the configuration of a second embodiment of the ablation debris removing device according to the present invention.

FIG. 3 is a schematic diagram illustrating the configuration of a third embodiment of the ablation debris removing device according to the present invention.

FIG. 4 is a schematic diagram illustrating the configuration of a fourth embodiment of the ablation debris removing device according to the present invention.

5 is an explanatory diagram of a configuration example in which the ablation debris removing device shown in FIG. 4 is attached to an ablation processing device and applied to processing of a color filter substrate that constitutes a liquid crystal display element.

FIG. 6 is an explanatory diagram of an ablation phenomenon schematically showing a shadow graph of an ablation phenomenon by a dye laser (pulse width of about 5 ns) delay-synchronized with a pulse of excimer laser light.

[Explanation of symbols]

 1 Suction Nozzle 2 Exhaust Portion 3 Suction Containers 3a, 3b Side Wall of Suction Container 4 Laser Light Incident Window 5 Suction Container Bottom Plate 6 Surface Workpiece 6'Color Filter Substrate 7 Color Filter Layer 7a Convex Section 8 Moving Table 9 Excimer Laser 10 Excimer laser light 11 Uniform illumination optical system 12 Irradiation laser light 14 Dielectric multilayer mask 18 Imaging optical system.

Claims (4)

[Claims] 1. An ablation debris removing device, comprising a vacuum suction device at a position facing an ablation processing part for irradiating an excimer laser beam, and removing and removing debris generated by the ablation. 2. The vacuum suction device according to claim 1,
An ablation debris removing device having at least one tubular nozzle, the ablation debris removing device being installed at a position on a workpiece where a velocity of a plume caused by the ablation is lower than a flow rate of vacuum suction. 3. The vacuum suction device according to claim 1,
Having an annular suction nozzle surrounding the ablation part,
An ablation debris removing device, characterized in that it is installed at a position on a workpiece where a plume velocity due to the ablation becomes slower than a vacuum suction flow velocity. 4. The vacuum suction device according to claim 1,
An entrance window made of a quartz material that transmits excimer laser light, and approximately 2 m from the area of the ablation processing part of the workpiece.
A bottom plate having an emission port wider than m and facing the incident window, an exhaust port connected to an exhaust system, an optical path of the excimer laser port between the exhaust port and the space between the incident window and the bottom plate. An ablation debris removing device comprising a nozzle-like structure having a flow velocity of 25 m / s or more in a portion deviated from the above, and the bottom plate is installed at a distance of approximately 1 mm or less from the workpiece.