JPH08277478A - Etching liquid circulator for laser induced wet etching - Google Patents

Abstract

PURPOSE: To prevent the degradation in a working rate by depressing the liquid surface height of an etching liquid by a transparent plate to allow the transmission a laser beam and circulating the etching liquid packed in a container part by a circulating path. CONSTITUTION: A container part 16 of a main body is provided with an aperture 18b atop this part, is arranged with a sample 104 on its rear surface and is packed internally with the etching liquid. A transparent plate 36 is disposed in the aperture 18b to depress the liquid surface of the etching liquid packed in the container part 16 and to allow the transmission of the laser beam. The etching liquid packed in the container part 16 is circulated by using a circulating path 20. The transparent plate 36 and the aperture 18b are put into a hermetic state by a sealing member 38. The transparent plate is formed of a transparent glass plate. As a result, the execution of the high-accuracy fine working is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for circulating an etching solution in laser-induced wet etching, and more particularly to a laser-induced wet etching apparatus for preventing a reduction in processing speed when performing laser-induced wet etching. -It relates to an etchant circulation device in etching.

[0002]

2. Description of the Related Art Conventionally, as a method of performing a fine etching process on a solid surface as a sample using a laser, a laser-induced dry method in which a sample is held in a container filled with an etching gas and irradiated with laser light. Etching and
Etching solution (hereinafter referred to as "etchant" as appropriate)
There is known a laser-induced wet etching in which a sample is held in a container filled with a laser beam and irradiated with laser light.

[0003] Laser induced dry etching is performed using an apparatus system as shown in FIG. In this apparatus system, a sample 104 is held in a gas cell 102 sealed by a transparent quartz glass plate 100, and after the gas cell 102 is evacuated to a vacuum state, an etching gas is sealed.

As an etching gas, a halogen compound is mainly used, and the etching gas may be sealed in the gas cell 102.
As shown in FIG. 1, an apparatus is used in which an etching gas flows during an etching process. That is, the pipe 10
6, an etching gas cylinder 114 and a gas cell 10 via a needle valve 108, a gas pressure gauge 110 for measuring the pressure of the etching gas, and a valve 112.
2 so as to allow the etching gas to flow from the etching gas cylinder 114 into the gas cell 102, and a valve 118 through the pipe 106.
Through the gas cell 102 to the outside.

After the gas pressure of the etching gas in the gas cell 102 is stabilized, the laser oscillator 120
The surface of the sample 104 is etched by irradiating the surface of the sample 104 with laser light emitted from the substrate. That is, the laser light emitted from the laser oscillator 120 is transmitted through the mirror 122 to the microscope irradiation device 1 via the mirror 122.
24. Then, the laser light incident on the microscope irradiation device 124 is introduced into the objective lens 128 via the mirror 126 of the microscope irradiation device 124, and the laser light is emitted from the objective lens 128 toward the sample 104, and the surface of the sample 104 Is performed.

The state of the etching of the sample 104 is monitored by a monitor (not shown).

The laser-induced dry etching performed by using the above-described apparatus system is suitable for performing fine processing on the order of wavelength, or for precisely controlling the depth direction at the atomic layer level. In particular, in the field of semiconductors, it is often not preferable to use a solution. Therefore, laser-induced dry etching has become mainstream.

On the other hand, laser-induced wet etching is performed using an apparatus system as shown in FIG.
Components that are the same as or correspond to those shown in FIG. 2 are denoted by the same reference numerals as those in FIG. 2, and detailed description of the detailed configuration and operation will be omitted as appropriate. In this system, the sample 104 is held in a sealed container 130 that is opened only on the upper surface filled with the etchant. By irradiating the surface of the sample 104 with laser light emitted from the laser oscillator 120, the sample 1
The surface of the substrate 04 is etched.

As the sample 104, almost any solid material such as a dielectric, a semiconductor, and a metal can be used.

As an etchant used for such laser-induced wet etching, an acid such as hydrochloric acid or sulfuric acid or an alkali solution such as potassium hydroxide is generally used. Compared to the laser-induced dry etching used,
The processing rate can be increased by one digit or more. This is because the density of the reaction solvent when using an etchant is higher than the density of the reaction gas when using an etching gas. For this reason, laser-induced wet etching is suitable for high-speed processing and when a deep processing depth is required, and is not suitable for fine processing on the order of wavelength, but is suitable for processing a line width about one order of magnitude larger than the wavelength. Is enough to respond.

In the apparatus system shown in FIGS. 2 and 3, the gas cell 102 holding the sample 104 and the base 132 or the microscope irradiating device 124 on which the closed container 130 is mounted are moved in the X direction, the Y direction, By appropriately moving in the Z direction, the surface of the sample 104 can be etched into a desired shape.

[0012]

However, in the above-described system for performing the laser-induced wet etching, when the sample 104 immersed in the etchant in the closed vessel 130 is deeply processed, the etching process proceeds. As a result, the amount of the reaction product increases, and the reaction product deteriorates the etchant. Therefore, there is a problem that the processing speed is saturated and decreases with the etching time.

In the above-described system for performing the laser-induced wet etching, when the sample 104 immersed in the etchant in the closed container 130 is subjected to high-precision fine processing, the sample 104 is held in the closed container 130. The reaction product stays inside the processing groove of the sample 104, and the reaction product and the unreacted etchant are not smoothly exchanged in the processing region, resulting in a problem that the processing speed is reduced.

Therefore, as a countermeasure for solving these problems, it is conceivable to always supply a fresh etchant to the processing area to replace a reaction product with an unreacted etchant. For this reason, it is understood that the etchant may be constantly circulated instead of being kept stationary in the closed container 130.

However, if the etchant is simply circulated, the flow of the etchant generates bubbles or waves on the liquid surface, which disturbs the liquid surface on which the laser beam is incident, and causes high-precision microfabrication. Cannot be performed.

The present invention has been made in view of such various problems of the prior art, and an object of the present invention is to perform laser-induced wet etching on the surface of a sample using a laser beam. When performing, while circulating the etchant filled in the container holding the sample and suppressing the generation of bubbles and liquid surface waving of the etchant filled in the container due to the circulation, the laser light is incident It is an object of the present invention to provide an etching liquid circulating apparatus for laser-induced wet etching, which suppresses a disturbance in the liquid level, prevents a reduction in processing speed, and enables high-precision fine processing.

[0017]

In order to achieve the above object, a laser etching apparatus according to the present invention comprises:
In an etchant circulating apparatus for laser-induced wet etching in which the surface of a sample is etched by using a laser beam and an etchant, an opening is provided on an upper surface, a sample is arranged on a lower surface, and an etchant is filled inside. A transparent plate that is disposed at the opening of the container portion, lowers the level of the etchant to be filled in the container portion, and transmits laser light, and is filled in the container portion. And a circulation path for circulating the etching solution.

[0018]

The circulation of the etching solution facilitates replacement of the reaction product with the unreacted etching solution, thereby preventing a reduction in the processing speed.

In addition, when such etching solution is circulated, even if bubbles are generated due to bubbles or fluctuations in the liquid level,
Since the liquid surface of the etching solution is pressed down by the transparent plate provided in the opening on the upper surface of the container, no bubbles or ripples are generated in the transparent plate.

Accordingly, the circulation of the etching liquid does not disturb the liquid level of the etching liquid on the lower surface of the transparent plate through which the laser light passes, so that the laser light irradiated on the surface of the sample has no influence. This makes it possible to circulate the etching solution without causing any problem and to perform high-precision fine processing without lowering the processing speed.

[0021]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an apparatus for circulating an etching solution in laser-induced wet etching according to the present invention;

FIG. 1 is a schematic structural view showing an etching liquid circulation apparatus in laser-induced wet etching according to the present invention. The same or corresponding structures as those shown in FIGS. The same reference numerals as those in FIG. 3 denote the same parts, and a detailed description of the detailed configuration and operation will be appropriately omitted.

In the etching liquid circulating apparatus 10 in the laser-induced wet etching, the sample 104 to be subjected to the laser-induced wet etching is an etching liquid circulating apparatus main body (hereinafter, simply referred to as “main body”) 12. Is held within.

The main body 12 includes a container body 16 filled with a predetermined etchant, a cover 18 covered on the upper surface of the container body 16, and a transparent quartz glass plate 3 provided on the cover 18.
6, and a circulation path 20 for circulating the etchant filled in the main body 12 is provided. The container body is constituted by the container body 16 and the lid 18.

A sample 104 is fixed to the bottom of the container body 16 via a holder 22. An inlet 24 and an outlet 26 for an etchant are provided on the side surface near the bottom of the container body 16. A discharge port 28 for extracting air from the main body 12 is provided above the inflow port 24 or the outflow port 26, and an air release valve 30 is provided in a discharge pipe 29 communicating with the discharge port 28. is set up.

The cover 18 is attached to the upper surface of the container body 16 by bolts 34 via a sealing material 32 such as an O-ring. A concave portion 18a having a diameter smaller than the inner diameter of the container body 16 is formed so as to lower the height of the liquid level of the filled etchant and maintain a predetermined distance between the etchant and the surface of the sample 104.
An opening 18b is formed in the opening.

A transparent quartz glass plate 36 is hermetically attached to the inside of the opening 18b formed in the concave portion 18a of the lid 18 via a sealing material 38 such as an O-ring. The attachment of the transparent quartz glass plate 36 to the opening 18b is performed by the following structure.

That is, a crank-shaped bracket 40 is formed to protrude downward from the inner surface near the opening 18 b of the lid 18, and the transparent quartz is provided on the locking portion 40 a of the bracket 40 via the cushion member 41. The lower surface of the glass plate 36 is placed. By inserting a sealing material 38 between the upper surface of the transparent quartz glass plate 36 and the inner surface near the opening 18b, the transparent quartz glass plate 3
6 will be mounted in a sealed state.

Accordingly, the main body 12 is filled with an etchant, and the height of the liquid surface of the etchant is set to the transparent quartz glass plate 3.
6 (for example, as shown in FIG. 1, the height of the liquid surface of the etchant is “H”), it is disposed in the concave portion 18 a formed in the central portion of the lid 18. The liquid surface of the etchant has been pushed down by the transparent quartz glass plate 36 thus formed. On the other hand, the etchant passes through the gap between the bracket 40 and the lower surface of the transparent quartz glass plate 36 and reaches the seal member 38 located on the upper surface of the transparent quartz glass plate 36.

Therefore, even if the etchant in the main body 12 flows, no bubbles or undulations occur on the lower surface of the transparent quartz glass plate 36.

The circulation path 20 for circulating the etchant is
A tank 42 for storing the etchant, a circulation pump 44, a filter 46 for filtering the etchant flowing out of the circulation pump 44, a flow control valve 48 for controlling the flow rate of the etchant, open / close valves 52, 5
4 and 56, and between them and between them and the main body 12 are connected by a Teflon pipe 50, and the etchant flows through the pipe 50.

Here, when filling and circulating the etchant in the main body 12, first, the open / close valves 52, 54, 56 of the circulation path 20 are closed, and the main body 12 is closed.
Air release valve 3 of discharge port 28 installed above
Open 0.

Next, with the air release valve 30 of the discharge port 28 opened, the open / close valves 52 and 54 of the circulation path 20 are opened.
Is opened, and the open / close valve 56 on the discharge side is closed. When the circulation pump 44 is driven by a motor (not shown), the etchant in the tank 42 is filtered through the filter 46 and then filled into the main body 12 from the inflow port 24. In this case, the outlet 2
Reference numeral 6 is closed by a valve (not shown).

When a predetermined liquid level in the main body 12 is filled with the etchant, a valve (not shown) of the outlet 26 is opened. Then, the etchant is returned from the outlet 26 through the flow control valve 48 into the tank 42, and is again circulated into the main body 12 by the circulation pump 44. Further, the air vent valve 30 of the discharge port 28
To prevent air from flowing in from the outside. At this time, the height of the liquid level of the etchant in the main body 12 is
The height is always maintained at a position higher than the upper surface of the transparent quartz glass plate 36 (for example, as shown in FIG. 1, the liquid level of the etchant is set to “H”).

In addition, an etchant that becomes dirty during the etching process or an etchant that becomes unnecessary after the process is completed is
By closing the open / close valve 54 communicating with the tank 42 side of the circulation path 20 and opening the open / close valve 56 communicating with the discharge side, it is possible to discharge to the outside.

As shown in FIG. 1, the laser light is emitted from the laser oscillator 120 and is applied to the microscope irradiation device 124.
The laser light emitted through the objective lens 128 of
The surface of the sample 104 is irradiated vertically through the transparent quartz glass plate 36.

In the above configuration, when etching the surface of the sample 104 using laser light, the sample 104 is held in the main body 12 and the height of the liquid level of the etchant in the main body 12 is reduced. , Transparent quartz glass plate 36
The surface of the sample 104 is irradiated with laser light emitted from the laser oscillator 120 while filling the etchant so as to be higher than the upper surface of the sample 104 and circulating the etchant by the circulation pump 44. Thereby, the sample 10
4 is etched.

As the etching process progresses, the etchant is degraded by the reaction product. However, since a fresh etchant in which the reaction product is filtered by the filter 46 is constantly circulated in the main body 12, A reduction in processing speed due to deterioration of the etchant is prevented.

In the case of performing fine processing, there is a possibility that a reaction product may stay in a processing groove portion as the etching processing proceeds. However, the flow of the etchant occurs in the main body 12 due to the circulation of the etchant. For,
The reaction product staying in the processing groove portion and the unreacted etchant can be easily replaced, and high-precision fine processing can be performed without lowering the processing speed.

Also, even if bubbles occur during circulation of the etchant or fluctuations occur due to fluctuations in the liquid level in the main body 12, a transparent quartz glass plate provided in the concave portion 18a formed in the center of the lid 18 is formed. Since the liquid surface is pressed down by the liquid crystal 36, no bubbles or undulations are generated on the transparent quartz glass plate 36, so that the laser beam applied to the surface of the sample 104 is affected. There is no.

The main body 12 according to the present invention may be either square or round. Depending on the type of etchant used, the main body 12 may be made of a vinyl chloride-based material or a corrosion-resistant metal. A material obtained by subjecting the surface of a material to Teflon processing or the like is appropriately used.

Further, it goes without saying that the piping used for the circulation path 20 of the etchant may be selected according to the etchant used.

[0043]

Since the present invention is configured as described above, it has the following effects.

Laser induced wet etching for etching the surface of a sample using a laser beam and an etchant
In an etching liquid circulation apparatus for etching, a container is provided with an opening on an upper surface and a sample is disposed on a lower surface, and an etching liquid is filled therein. Since it has a transparent plate that lowers the level of the etchant and transmits laser light, and a circulation path that circulates the etchant filled in the container, the etchant circulates, The replacement of the product with the unreacted etchant is easily performed, and a reduction in the processing speed can be prevented.

In addition, when such etchants are circulated, even if ripples occur due to bubbles or fluctuations in the liquid level,
Since the liquid surface of the etchant is pressed down by the transparent plate arranged at the opening on the upper surface of the container, bubbles and ripples do not occur in the transparent plate, so that the etchant circulates. Since the liquid level of the etchant on the lower surface of the transparent plate through which the laser light is transmitted is not disturbed, the etchant can be circulated without any influence on the laser light irradiated on the surface of the sample. Thus, high-precision fine processing can be performed without lowering the processing speed.

[Brief description of the drawings]

FIG. 1 is a schematic partial cross-sectional explanatory view showing an etchant circulation device in laser-induced wet etching according to the present invention.

FIG. 2 is a schematic partial cross-sectional explanatory view showing an apparatus system used for conventional laser-induced dry etching.

FIG. 3 is a schematic partial cross-sectional explanatory diagram showing an apparatus system used for conventional laser-induced wet etching.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 etching liquid circulation device 12 main body 16 main body container 18 lid 18 a recess 18 b opening 20 circulation path 36 transparent quartz glass plate 38 sealing material 46 filter 104 sample 120 laser oscillator 124 microscope irradiation device 128 objective lens

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Akira Moro 8-20-37-501 Nobomu, Niiza-shi, Saitama

Claims (4)

[Claims] 1. An etching liquid circulation apparatus for laser-induced wet etching for etching a surface of a sample using a laser beam and an etching liquid, wherein the sample has an opening on an upper surface and a sample is disposed on a lower surface.
A container portion in which an etching solution is filled, and a transparent plate disposed at the opening of the container portion and transmitting a laser beam while depressing the liquid level of the etching solution to be filled in the container portion. A circulation path for circulating the etching solution filled in the container portion.
An etchant circulation device for etching. 2. The transparent plate and the opening are disposed in a sealed state by a seal member disposed between an upper surface of the transparent plate and an inner surface near the opening of the container. 2. The liquid level of the etching solution is set to a height at which the etching solution reaches the sealing member.
An etchant circulation device for laser-induced wet etching as described. 3. The laser-induced wet etching according to claim 1, wherein a predetermined distance is maintained between the transparent plate and the sample placed in the container. Etchant circulation device. 4. The apparatus for circulating an etching solution in laser-induced wet etching according to claim 1, wherein the circulation path includes a filter for filtering the etching solution.