KR100568159B1 - Photo-assisted etching technique of gold and apparatus for the same - Google Patents

Abstract

The present invention relates to a gold etching method using light irradiation, and to provide a simple device and a gold etching method using a chemical material that is not harmful to the human body or the environment and simplified the process and an apparatus used therefor. A gold etching apparatus for achieving the above object is a container having a light transmitting window formed on one wall and filled with a chlorine-containing fluid, a specimen mounting portion for mounting a specimen in the container, and provided outside of the container and transmitting the light. And a light source for irradiating light toward the window. In such a device, gold is etched by irradiating light onto a specimen such as a substrate on which a gold or gold thin film is formed on a surface thereof.

Gold, etching, pattern, chlorine, gold chloride, ultraviolet,

Description

Gold etching method using light irradiation and device therefor {PHOTO-ASSISTED ETCHING TECHNIQUE OF GOLD AND APPARATUS FOR THE SAME}

BRIEF DESCRIPTION OF THE DRAWINGS The process chart explaining the normal patterning process.

2A is a schematic cross-sectional view of an apparatus for gold etching according to Embodiment 1 of the present invention.

FIG. 2B is a detailed cross-sectional view of the gold etching portion in the apparatus shown in FIG. 2A. FIG.

3A is a schematic cross-sectional view of an apparatus for gold etching according to Embodiment 2 of the present invention.

3B is a detailed cross-sectional view of the gold etching site in the device shown in FIG. 3A.

4 is a schematic cross-sectional view of a variant of the apparatus shown in FIG. 3A.

<Explanation of symbols for the main parts of the drawings>

100: substrate

110, 160: gold thin film

130: mask

150: substrate

200: light source

210: ultraviolet light

300, 400: container

310: light transmission window

320: chlorine-containing fluid

330: specimen mounting

410: sealing material

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of etching gold using light irradiation, and more particularly, to an etching method of a gold thin film which can be used in conducting wires or nanoscale patterning of integrated circuits in various microelectronic fields including semiconductors and communication. .

The metal thin film layer of the integrated circuit has been gradually changed to copper to increase the speed and conductivity while using tungsten or aluminum, and recently, an attempt has been made to change it to gold due to better conductivity. Moreover, gold is already used as a circuit material in high-power communication chips. In order to shape the metal layer of the integrated circuit as desired, etching the image after forming a mask or direct irradiation may form a gold pattern having a desired shape (FIG. 1). Gold cleaning and gold extraction can be used as examples of scanning electron microscopes (SEMs) used to measure nanometer-level patterns. do. In the future, many biochips, etc., will also use specimens coated with thin gold films. The gold used as a thin film can be cleaned and extracted to reuse the gold.

In order to form a specific pattern thereon using a gold thin film, an etching process is essential. For this, wet etching using a chemical solution and dry etching using a plasma are used. In the case of wet etching, chemical solutions harmful to the human body or the natural environment, such as H ₃ PO ₄ , KCN, HNO ₃ , and KI-I ₂ complexes, are mainly used, and a large amount of water is required to clean them. In the case of dry etching, milling using accelerated ions in a vacuum chamber or reactive ion etching (RIE) using plasma are used. In such etching, gold is mainly formed in a thin film form and is used to form a microstructure pattern in an integrated circuit configuration, MEMS (Micro Electro Mechanical System), and nano technology through a patterning process.

The patterning process should be followed by an exposure process in addition to the etching process, which is shown in FIG. 1 as a conventional conventional patterning process. In order to form a pattern on the substrate 100 on which the gold thin film 110 is formed on the surface as shown in FIG. 1A, the gold thin film 110 on the gold film 110 of the substrate 100 is formed as shown in FIG. The photosensitive agent 120 is applied to the film. On the substrate 100 on which the gold thin film 110 is formed and the photosensitive agent 120 is applied, a mask 130 having a predetermined pattern is positioned and irradiated with light 210 to expose the light only to the photosensitive agent 120a. (FIG. 1C). After the exposure process, the photosensitive agent 120a is removed in the pattern of the mask 130 (FIG. 1D). Then, as described above, the gold thin film 110a exposed between the photosensitive agents is removed by a wet etching method using a chemical solution or a dry etching method using a plasma or the like (FIG. 1E). After etching, the remaining photoresist is removed (FIG. 1F) to form a desired pattern on the gold thin film.

The patterning process of the gold thin film substrate by the conventional method has to go through several steps such as application of a photoresist, exposure for patterning the applied photoresist film, gold etching, photoresist removal, and the like. In particular, the patterning process requires several processes and materials for applying a photoresist on gold, exposing the photoresist, and then selectively etching the photoresist and gold. Thus, the patterning process is not only complicated but also requires a number of working steps to increase productivity. Lowers and increases production costs. In addition, patterned etching requires protecting devices and process materials from being etched. Since gold itself is chemically stable, it is difficult to find chemicals that selectively etch gold alone.

Moreover, the gold etching process poses significant environmental pollution problems such as harmful effects to the human body or the environment when wet etching is used, and requires a lot of industrial water to wash chemicals in the specimen during the process. Moreover, in order to solve this problem, there are many problems in terms of process cost due to continuous generation of wastewater and chemicals, which are by-products of the process.

In addition, in the case of dry etching using plasma or ions in a vacuum chamber, environmental problems and maintenance costs are solved somewhat, but expensive equipment is used, which does not contribute to a reduction in production cost. Moreover, the vacuum process itself is complicated by the process of putting the specimen into a vacuum chamber to increase the degree of vacuum using a vacuum pump, etching the gas into the chamber and etching it by plasma or ion generation, and then releasing the vacuum to take out the specimen. Very uncomfortable. Both of these etching methods have several problems because the process is inconvenient and the problem of treatment of residual materials after the process has to be solved.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and provides a simple device and a gold etching method using a chemical that is not harmful to a human body or the environment, and an apparatus used therefor.

It is another object of the present invention to provide a gold etching method and apparatus used therefor that can simplify the process to improve productivity and reduce manufacturing costs.

The inventors of the present invention discovered a phenomenon in which gold is etched by putting gold in a solution or a solvent containing chlorine and irradiating light, preferably ultraviolet rays. Thus, the present invention uses this phenomenon to etch a thin film of gold on the substrate on which the thin film is formed, or to add gold to gold patterning, gold surface cleaning or gold extraction. Herein, a solution or a solvent containing chlorine refers to all liquid and gaseous substances including chlorine, such as brine (NaCl), weak hydrochloric acid (HCl), organic solvent dichloroethane, or a mixture of two or more thereof. The present invention may use such a solution as well as a gas containing chlorine, for example gaseous chlorine (Cl ₂ ).

The preferred embodiments of the present invention will be described in detail below with reference to the drawings.

Example 1

2A and 2B are schematic views for etching gold in a gold specimen or a substrate on which a gold thin film is formed on a surface according to Example 1 of the present invention, and for explaining the operation of the gold etching portion in such a device. For the gold etching according to the first embodiment of the present invention, a chlorine-containing fluid 320 such as a solvent or a gas or a solution containing chlorine described above in a container 300 in which a light transmitting window 310 such as glass is formed on one wall is formed. To charge. A specimen mounting portion 330 is provided on the bottom, the upper wall, or the sidewall of the container to fix and mount the substrate 100 on which the gold specimen or the gold thin film 110 is formed. The light source 200 is installed outside the container 300 to irradiate light to the substrate 100 in the container 300 through the light transmitting window 310. At this time, the light source 200 is preferably an ultraviolet light source. Meanwhile, in order to etch the surface of the gold thin film 110 in a predetermined pattern, a photographic disc or mask 130 having a predetermined pattern formed between the light transmitting window 310 and the light source 200 may be installed.

A process for gold etching using such an apparatus is described below with reference to FIG. 2B. First, the substrate 100 on which the gold thin film 110 for gold etching is formed is mounted on the specimen mounting part 330. In this case, the substrate 100 is fixedly mounted such that the surface on which the gold thin film 110 to be etched is formed toward the light transmitting window 310. The ultraviolet light 210 irradiated from the light source 200 outside the container 300 passes through the light transmitting window 310 in a predetermined pattern engraved in the mask 130 while passing through the mask 130. As such, the ultraviolet light 210 passing through the mask 130 and the light transmitting window 310 reaches the surface of the gold thin film 110 of the substrate 100 in a predetermined pattern form. At this time, the ultraviolet light 210 promotes the reaction of chlorine and gold in a solution or a solvent to form gold chloride so that gold chloride is separated from the substrate 100 to etch gold. By using the mask as described above, the patterning process is easily performed on the substrate on which the gold thin film is formed by etching only a desired portion.

Meanwhile, a predetermined pattern formed on the mask 130 may be formed on the surface of the light transmitting window 310. In addition, the gold surface may be cleaned by etching light on the entire substrate (or part of the substrate) without installing the mask 130. The cleaned gold is treated differently, so it is possible to extract only pure gold.

Example 2

The gold etching method using light irradiation according to Example 1 is possible when the fluid containing chlorine used for gold etching transmits ultraviolet rays. If the fluid used absorbs ultraviolet light like ordinary water and the ultraviolet light cannot penetrate the fluid, gold etching becomes impossible.

Typically, the extent to which ultraviolet light penetrates the fluid depends on the concentration (or purity) of the substance contained in the fluid, including chlorine, and the distance the light has passed through the fluid. Therefore, even if the ultraviolet rays reach the gold surface through the fluid, even if the fluid absorbs some of the ultraviolet rays, if the path is short, a considerable amount of ultraviolet rays reach the gold surface, but the path through the fluid even if the absorption is weak. The longer the absorption occurs. That is, the extent to which ultraviolet light is absorbed is represented by the product of the fluid's optical properties (extinction coefficient) and the total distance through the fluid. For example, high purity water passes ultraviolet rays, while ordinary water absorbs ultraviolet rays. In addition, when the grain component (colloidal state) is present in the solution or the solvent, scattering is severe and the pattern formed on the mask may not be accurately formed on the substrate when gold thin film patterning is performed using the mask.

  In Embodiment 2 described below, the above problem is solved.

In the above case, in the present embodiment, the gold to be etched should be a thin gold thin film so as to transmit light, and when the gold thin film is applied to one surface of the substrate, the substrate should have a light transmittance like glass.

First, in the case of patterning the gold thin film 160 coated on one surface of the glass substrate 150 using the same apparatus as described above, the gold thin film 160 is mounted when the substrate is mounted on the specimen mounting portion 330. It is the same as the first embodiment except that the back surface of the uncoated substrate 160 is fixedly mounted so as to face the light transmitting window 310. As such, when the glass substrate 150 coated with the gold thin film 160 is mounted in the container 300, as illustrated in FIG. 3B, the ultraviolet light 210 emitted from the light source 200 may be a mask (the photo disc). The gold thin film 160 is irradiated through the rear surface of the glass substrate 150 on which the gold thin film 160 is not formed. In this case, the ultraviolet light 210 promotes the reaction of chlorine and gold in the chlorine-containing fluid to form gold chloride so that gold chloride is released from the substrate 150 to etch gold. As such, when using the apparatus described in Embodiment 1 described above, the chlorine-containing fluid is preferably sealed between the glass substrate 150 and the light transmitting window 310.

On the other hand, as shown in FIG. 4, the glass substrate 150 is installed in the container 400 having one wall surface instead of the light transmitting window 310 so as to face the inside of the container. You can also do In this case, the sealing material 410 may be interposed between one wall surface of the container 400 and the glass substrate 150 to prevent the chlorine-containing fluid from leaking to the outside.

The gold etching method according to the above-described configuration is environmentally friendly and does not incur any costs for the post-treatment of such chemicals as compared with conventional wet etching because it does not use chemicals harmful to humans or the environment. In addition, compared to dry etching, which requires an expensive vacuum device and a plasma generating device, a simple pattern is formed by irradiating gold, which is placed in a fluid containing chlorine, with light such as ultraviolet light to form a complicated pattern of exposure and patterning. Simplification brings economic and time benefits.

Claims (12)

In the apparatus for gold etching for etching a specimen such as a substrate on which a gold or gold thin film is formed on the surface, A container having a light transmitting window formed on one wall and filled with a chlorine-containing fluid, A specimen mounting portion for mounting the specimen in the container; And a light source provided outside the container and irradiating light toward the light transmitting window. In the gold etching apparatus for etching a specimen such as a light transmissive substrate formed on the surface of a gold or gold thin film having a thickness enough to transmit light, A container with one wall open and filled with chlorine-containing fluid, A specimen mounting portion for mounting the specimen on the open wall of the container; And a light source provided outside of the container and irradiating light toward the open wall surface. The apparatus of claim 2, further comprising a sealant between the open wall and the specimen to seal therebetween. The gold etching apparatus of claim 1 or 2, wherein a mask having a predetermined pattern is provided between the container and the light source. In the gold etching method for etching a specimen such as a substrate on which a gold or gold thin film is formed on the surface, Mounting the specimen in a chlorine containing fluid; Gold etching method comprising the step of irradiating the specimen with light. The method of claim 5, wherein the chlorine-containing fluid comprises any one of brine (NaCl), weak hydrochloric acid (HCl), dichloroethane, gaseous chlorine, and a mixture of two or more thereof. The gold etching method according to claim 5 or 6, wherein the light is ultraviolet light. The method according to claim 5 or 6, wherein the specimen is a thin film having a thickness enough to transmit light is formed on one surface of the transparent substrate, the step of irradiating light to the specimen is a transparent substrate without a gold thin film is formed Gold etching method comprising the step of irradiating the back. The method according to claim 8, wherein the chlorine-containing fluid is filled in a container having a light transmission window formed on one wall, and mounting the specimen in the chlorine-containing fluid is a rear surface of the light transmissive substrate on which the gold thin film is not formed Gold etching method comprising the step of contacting. 10. The method of claim 9, wherein contacting the backside of the light transmissive substrate with the light transmissive window comprises sealing between the light transmissive substrate and the light transmissive window. The gold etching method of claim 5 or 6, wherein the irradiating light onto the specimen is irradiated onto the specimen after the light passes through a mask having a predetermined pattern. The gold etching method of claim 5 or 6, further comprising extracting gold etched by the gold etching.

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