KR100735449B1 - A method for manufacturing micro-reformer for fuel cell - Google Patents

Abstract

A micro-reformer manufacturing method which prevents the leakage of fuel from a reformer more certainly and further improves the efficiency of the reformer accordingly by increasing compactness of the bonding structure of a catalyst layer and a glass anodic bonding is provided. A method for manufacturing a micro-reformer(1) using a silicon wafer(10) comprises: a first step of forming a channel(20) for fuel evaporation and hydrogen reforming in the reformer; a second step of forming a heating wire(40) in a lower part of the wafer; a third step of coating a first dry film photoresist(50) on an upper surface of the wafer, and removing the dry film photoresist on a channel portion; a fourth step of coating a first catalyst layer(70) on the channel and the first dry film photoresist, and heat treating the first catalyst layer; a fifth step of removing portions of the first catalyst layer and the first dry film photoresist other than the channel, and coating a second dry film photoresist(50'); a sixth step of coating a second catalyst layer on upper surfaces of the first catalyst and the second dry film photoresist, and heat treating the second catalyst layer; a seventh step of removing portions of the second catalyst layer and the second dry film photoresist other than the channel; and an eighth step of bonding a glass anodic bonding(80) onto upper and lower surfaces of the wafer.

Description

Reformer manufacturing method {A Method for Manufacturing Micro-Reformer for Fuel Cell}

1 is a schematic perspective view showing a (ultra) small reformer using a wafer on which a flow path is formed

2 is a structural diagram illustrating a fuel leak problem in a reformer in which a flow path is formed on a conventional wafer and glass is bonded.

Figure 3 is a schematic diagram for explaining the reformer manufacturing step according to the present invention

Figure 4 is a main view showing the tight bonding state between the catalyst layer and the glass in the micro reformer using a wafer prepared in the manufacturing step according to the present invention.

Figure 5 (a) and (b) is a photograph showing the coating state of the DRF film (Dry Film Photo Resist) used in the reformer manufacturing step of the present invention

Explanation of symbols on the main parts of the drawings

1 .... the reformer produced by the manufacturing step of the present invention

10 ... wafer 20 ... Euro

30 ... insulation layer 40 ... heating wire

50,50 '.... DRF Film 60,70 .... Catalyst Layer

80 .... Glass (layers)

The present invention relates to a reformer for supplying fuel (hydrogen gas) to a power generation cell of a fuel cell, in particular, a method of manufacturing a micro reformer in which a flow path is formed on a wafer, and more particularly, a catalyst layer coated on a flow path formed on a wafer. Impurity (impurity) generated during the coating of the dry film photoresist (Dry Film Photo Resist) (hereinafter referred to as 'DFR Film') to remove the coating in the manufacturing process by cleaning, the catalyst layer and the glass bonding layer ( The present invention relates to a reformer manufacturing method of improving the compactness of the adhesive part of glass anodic bonding, thereby preventing fuel leakage from the reformer and improving the efficiency of the reformer.

With the depletion of energy and environmental problems, the development and attention of fuel cells with high energy efficiency and low environmental pollution are focused. Such fuel cells not only enable energy replacement but also hydrogen, etc. Because it generates electricity by directly oxidizing fuel, it is recognized as a representative of future energy because it provides other important environmentally friendly advantages that the noise generated during operation is very low and pollutants are generated little.

In addition, a fuel cell is defined as a cell (cell) having the ability to directly convert the chemical energy of the fuel into electrical energy to produce a direct current, and unlike the conventional cell, the fuel cell continuously supplies electricity by supplying fuel and air from the outside. There is a difference in producing.

In addition, since direct current power is generated while electrons pass through the electrolyte (membrane), heat is additionally generated, which is also useful in terms of heat recycling.

In addition, the fuel of the fuel cell uses hydrogen gas generated through a process of reforming using pure hydrogen or hydrocarbons such as methanol, and the like. Reforming Apparatus or reformer related to the invention.

On the other hand, fuel cells can be divided into various types: phosphate acid fuel cell (PAFC), alkaline fuel cell (AFC), and polymer electrolyte fuel cell (Proton Exchange Membrane Fuel). Cell (PEMFC), Molten Carbonate Fuel Cell (MCFC), Solid Oxide Fuel Cell (SOFC), and Direct Methanol Fuel Cell (DMFC) In the following description, the fuel cells are described in English abbreviation.

In addition, as the use of mobile communication terminals, notebook computers, or portable multi-computers is rapidly increasing among these various types of fuel cells, research on fuel cells for supplying power to devices is also being concentrated.

However, as portable devices such as laptops and mobile phones are not only capable of improving functions and services, in particular, miniaturization of devices is a main concern, so miniaturization of fuel cells used in portable devices is a major concern of R & D.

On the other hand, among the various types of fuel cells described above, the most widely researched and practical applications of small (micro) fuel cells mounted on portable devices are DMFC and PEMFC (PEFC).

In this case, DMFC and PEMFC use methanol and hydrogen as fuels, respectively, and accordingly, the performance and fuel supply system of the fuel cell are different from each other, and have advantages and disadvantages.

However, since the DMFC is significantly lower than the PEMFC in terms of output density, it is being researched for power supply of portable devices, but its actual utilization value is being lowered.

On the other hand, since PEMFC (PEFC) uses hydrogen as a fuel, it is necessary to use a reformer for reforming a fuel such as methanol to hydrogen gas and supplying it to a fuel cell (power cell). Except for size issues, it is known to be advantageous for power supply of portable devices in terms of power density.

Therefore, in the case of fuel cells for portable devices, especially PEMFC, miniaturization of the reformer and reduction of the mounting (mounting) area of the actual device have been researched.

On the other hand, if the fuel is classified only as a basis, it can be classified into a direct methanol fuel cell (DMFC) and a reformed hydrogen fuel cell (RHFC).

That is, as described above, DMFC and RHFC use the same components and materials, but use different methanol and hydrogen as fuels, and thus have different advantages and disadvantages in fuel cell performance and fuel supply. RHFC offers significant advantages in terms of power density, other than system size, compared to DMFC.

On the other hand, since solving the size problem has advantages in RHFC, such as output density, researches using semiconductor process technology and MEMS technology have been concentrated for the size problem of RHFC, that is, miniaturization.

In other words, a method for fabricating a multi-area micro fuel cell using wafer processing technology and reforming fuel to directly supply hydrogen to a micro fuel cell in order to form an output density has been developed. Such a small reformer has a high output density. By producing hydrogen gas and supplying it to power cells (fuel cells), the output density is increased while the size is reduced.

For example, FIG. 1 illustrates a (ultra) small reformer using a wafer. The ultra-small reformer 100 such as an evaporator uses a silicon wafer substrate 110 and evaporates reforming an aqueous methanol solution to hydrogen gas. The flow path (channel) 120 of the region and the reformed region is formed.

By the way, in the case of PEMFC having good output density, the wafer substrate 110 is used as an integrated reformer to reduce the size, but as a prerequisite, a methanol solution, which is a fuel, or hydrogen gas, which is a fuel of a cell in which the gas is reformed. Bonding densities should be increased to suppress external leakage.

However, as shown in FIG. 2, the flow path 120 is formed on the wafer substrate 110 of the conventional micro reformer 100, and the insulating layer 130, the catalyst layer 140, and the heating wire 160 are provided. By bonding the glass (layer) 150, in the bonding region between the catalyst layer 140 and the glass layer 150, which is part 'A' of FIG. 2, impurities generated during coating and removal of the catalyst layer are bonded. There was a problem that gas leakage was easily generated while weakening the compactness of the structure.

Therefore, in the case of the reformer 100 of FIG. 2, a serious problem of reducing the efficiency of the reformer occurs due to leakage of fuel (methanol / hydrogen gas).

Therefore, in order to densify the bonding structure, it is necessary to remove impurities generated during coating of the catalyst layer.

On the other hand, a technique for improving the adhesion of the substrates by preventing the catalyst from being coated on the bonding area when coating the catalyst is disclosed in Japanese Patent Laid-Open No. 2004-290879.

That is, although not shown in a separate drawing, the publication removes an adsorption film of a portion other than the bottom of the groove portion of the substrate by depositing a metal oxide film on the bottom of the groove portion of the first substrate and polishing the surface of the substrate. The catalyst-containing liquid containing the catalyst is applied to the adsorption membrane, so that the adsorption membrane remaining on the bottom of the groove adsorbs the catalyst so that the catalyst-containing liquid is not formed in a region other than the groove portion, whereby the second substrate and the first substrate The technique which improves the bonding property of is disclosed.

In other words, after the metal oxide film is applied, a catalyst layer is formed thereon so that the catalyst layer is not formed in the substrate bonding region.

However, in the prior art, it is difficult to completely block the penetration into the junction region by adsorbing the catalyst-containing liquid and remaining only in the grooves.

Accordingly, if the catalyst containing liquid is coated as in the prior art, but other coatings are removed to clean the catalyst layer in the bonding region, residual impurities in the bonding region are always removed regardless of an error occurring in the formation of the catalyst layer. It would be desirable to provide a more compact bonding structure.

In other words, if a catalyst is formed on the wafer flow path, the DFR film, which is a removal material, is coated on the part other than the flow path, and it is dissolved and washed with acetone and pure water to remove the portion other than the flow path. Since the bonding density between a catalyst layer and a glass layer can be improved, it is preferable, and the technique of manufacturing such a reformer has been required.

The present invention is to solve the above-mentioned conventional problems, to improve the compactness of the bonding structure of the catalyst layer and the glass layer (glass anodic bonding) to more surely prevent fuel leakage in the reformer, thereby improving the efficiency of the reformer It is to provide a reformer manufacturing method to further improve the.

As a technical aspect for achieving the above object, the present invention, a method for manufacturing a reformer using a silicon wafer, the first step of forming a flow path for fuel evaporation and hydrogen reforming on the wafer;

A second step of forming a hot wire under the wafer;

A third step of coating a first DFR film on the upper surface of the wafer and removing a DFR film of a flow path portion;

A fourth step of coating heat treatment of the first catalyst layer on the flow path and the primary DFR film;

A fifth step of removing portions other than the flow path of the first catalyst layer and the first DRF and coating a second DFR film;

A sixth step of coating and heat treating the second catalyst layer on the first catalyst layer and the second DFR film;

A seventh step of removing portions other than the flow path of the second catalyst layer and the second DFR film; And,

An eighth step of bonding a glass layer on the lower surface of the wafer;

It provides a reformer manufacturing method comprising a.

In this case, it is preferable that a protective film for protecting the surface of the wafer is deposited by CVD before the first step.

In addition, the flow path of the first step is formed by etching the wafer using an induced couple plasma (ICP) method after application, exposure and etching of PR.

Here, platinum is deposited by sputtering through the application, exposure, and etching of PR to a cavity etched with an etching solution on the lower part of the wafer, and then PR except for the heating wire is removed.

In addition, it is preferable to form an insulating layer on the wafer surface after the first step by CVD.

The first and second DFR films are coated with a roller coater and removed by acetone application and pure water washing.

Finally, the first catalyst layer of the fourth step is spray coated with Al ₂ O ₃ which maintains the catalytic function of the second catalyst layer, either CuO or ZnO, which is spray coated thereon in the next sixth step. .

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a schematic view illustrating a reformer manufacturing step according to the present invention, and FIG. 4 is a principal view illustrating a precise bonding state between the catalyst layer and glass in a micro reformer using a wafer manufactured by the manufacturing step according to the present invention. 5 (a) and 5 (b) are photographs showing a coating state of a DRF film (Dry Film Photo Resist) used in the reformer manufacturing step of the present invention.

First, the ultra-compact reformer for battery according to the present invention (1 in FIG. 3K) is a wafer bonding surface while eliminating the bonding density generated in the existing reformer, that is, the bonding density in the catalyst layer and the glass layer bonding region caused by the catalyst layer impurities. It is characterized by improving the efficiency of reformer by providing fuel cleaning environment and ultimately suppressing the leakage of fuel gas.

Meanwhile, the micro reformer 1 for fuel cells of the present invention described below uses a methanol solution through an evaporation / catalyst reaction to supply hydrogen gas to a PEMFC using hydrogen (gas) as a main fuel among various types of fuel cells. The reformer is reformed by hydrogen gas.

Next, the step of explaining the reformer manufacturing step according to the present invention based on Figure 3 as follows.

First, as shown in FIG. 3A, after cleaning the silicon wafer 10 (si wafer), the Si ₃ N ₄ (12) is chemically grown using a protective film to protect the wafer surface. And chemical vapor deposition (hereinafter referred to as 'CVD').

On the other hand, such a CVD method is known, for example, a method used for forming a thin film on a substrate in a manufacturing process such as IC.

Next, as shown in FIG. 3B, a photoresist (hereinafter referred to as 'PR') 14 to form a cavity 16 for thermal linearization under the wafer 10. After coating, the Si ₃ N ₄ (12), which is a protective film of the hot-wire deposited portion for forming the cavity, is removed through a normal exposure and etching process.

On the other hand, PR is a photoresist film, a developer having a property of changing the solubility of the irradiated portion when irradiated with ultraviolet rays. It is used to form and etch.

For example, in the process of manufacturing a semiconductor device such as a large scale integrated circuit (LSI), it is one of the element processes in which techniques such as thin film formation, photolithography, etching, and ion implantation are applied to a semiconductor single crystal wafer. The electrode material attached to the surface of the wafer is etched by the pattern formed by photolithography. Until now, the wet etching method using chemicals has been performed. However, since the mid 1970s, dry etching ( dry etching) is mainly used.

Next, as shown in FIG. 3C, the PR 14 is removed while the cavity 10 is formed by etching the wafer 10 on the hot wire deposition region with an etching solution such as TMAH or KOH.

Next, as shown in FIG. 3D, the PR 14 ′ is formed on the wafer 10 to form a flow path 20 for substantial methanol evaporation and reforming to hydrogen gas through catalysis of the evaporated gas. After the application, exposure and etching of the wafer, the wafer is etched by an ICP (Induced Couple Plasma), that is, an inductively coupled plasma method to form a flow path 20 (see 120 in FIG. 1).

Next, as shown in FIG. 3E, the residual PR of the upper surface of the wafer 10 is removed, and the SiO ₂ layer of the insulating layer for preventing the energization of the wafer flow path, the lower cavity, and the wafer surface by the CVD method described above ( 30), and after application, exposure and etching of the hot wire PR 14 ″, the hot wire 40 of platinum Pt is formed by a sputtering method.

On the other hand, such a heating wire 40 serves to maintain the proper temperature during the reforming of the hydrogen gas by the catalytic reaction of the evaporation of the methanol solution and the reforming portion of the evaporated methanol by heating the initial evaporator and the reformer during the actual reformer operation.

Next, as shown in Figure 3f, after coating the first DFR film 50 on the wafer top, through exposure (for example UV 3 minutes), etching (5 minutes showering with Na ₂ CO ₃ solution) through The DFR film 50 of only the flow path portion is removed, and the PR 14 "

In this case, the DFR Film 50 is a known PET film form by coating the coating at about 80 ℃ while pushing the roller-type coating machine.

Next, as shown in FIG. 3g, the Al ₂ O ₃ seed layer 60, which is the first catalyst layer 60, is coated on the flow path 20 and the primary DFR film 50 by a spray method. Heat treatment (about 2 hours at 500 ℃).

In this case, the Al ₂ O ₃ seed layer, which is the first catalyst layer 60, is a catalyst safety layer that stably maintains the catalytic function of the second catalyst layer 70 such as CuO and ZnO, rather than contributing substantially to the catalytic reaction. It is provided as, but described as the first catalyst layer.

Next, as shown in Figure 3h, after the Al ₂ O ₃ layer 60 is formed, the residual primary DFR film 50, except for the passage portion, is removed with acetone and washed with pure water.

In this case, since the first catalyst layer, which affects the compactness of the bonding structure, is removed along with the DFR Film 50 except for the passage portion, in particular, the next glass bonding layer portion is cleaned, the bonding density due to residual impurities in the first catalyst layer It is to prevent weakening.

Next, the second DFR Film 50 'is coated and patterned in the manner described above.

Next, as illustrated in FIG. 3I, a catalyst layer 70 is coated on the wafer upper surface by spraying on the Al ₂ O ₃ layer 60 and the secondary DFR film 50 ', followed by heat treatment (approximately 300 ° C.). 2 hours).

As shown in FIG. 3J, after forming the catalyst layer 70, the residual secondary DFR film 50 ′ is removed with acetone together with the catalyst layer 70 except the flow path and washed with pure water.

Therefore, impurities in the bonding region of the catalyst layer 70 are treated to be cleaned upon removal of the secondary DFR film 50 ', and as a result, coating layers other than the flow paths of the first and second catalyst layers 60 and 70 are removed. Enables densification of the bonding structure.

In addition, since the residual catalyst coating layer does not remain except the flow path portion, it contributes to the miniaturization of the reformer as a whole.

Next, as shown in FIG. 3K, the final Pyrex glass 80 is bonded to the bonding region where the bonding region is cleaned.

Therefore, the ultra-compact reformer 1 of the present invention manufactured using the DFR film described so far has a conventional metal oxide film (adsorption film) formed in the groove portion (euro), thereby controlling the coating area of the catalyst when coating the catalyst layer. By completely removing portions other than the flow path of the catalyst layer, impurities in the bonding region are more excellent.

That is, as shown in Figure 4, the catalyst layer 70 for reforming the methanol gas to hydrogen gas by substantially catalytic reaction with the Al ₂ O ₃ layer 60, which is the first catalyst layer of the 'B' portion of the first and second When the glass (layer) 80 of Fig. 4 is bonded (adhesive C), since the portions other than the flow path in the 'L' direction with the DFR Films 50 and 50 'are removed without any impurities remaining to be cleaned. Bonding density is excellent.

As a result, since the bonding density between the glass layer 80 and the catalyst layers 60 and 70 is made, the bonding force is increased by that, and the leakage of the reformed hydrogen gas reforming the methanol solution is effectively prevented.

Meanwhile, in FIG. 5, the secondary DFR film 50 ′ re-coated on the outside of the flow path 20 after the KOH etching process is shown in a photograph. Here, the deep red portion is the DFR Film 50 'portion, and the remaining rough portions represent the KOH etching-etched flow path 20.

Therefore, since the portion of the catalyst layer excluding the flow path surface is also cleaned through the removal of acetone and pure water during the removal of the DFR film 50 ', the densification of the glass bonding due to impurities is improved.

At this time, it is common to use CuO and ZnO as the catalyst layer.

Meanwhile, in FIG. 1, platinum or palladium (Pd) or the like, which enables to remove CO in hydrogen gas, may be further coated on the flow path surface at the outlet portion of the reformed hydrogen gas.

In this case, since CO, which causes poisoning of the catalyst provided in the power generation cell of the fuel cell, is removed in the reformer of the present invention, it is possible to produce hydrogen gas of higher purity, thereby improving fuel cell characteristics.

According to the present reformer manufacturing method as described above provides the following effects.

First, it is possible to effectively prevent the fuel leakage (leakage) of the reformer affecting the fuel cell efficiency, it is possible to improve the performance of the reformer.

Secondly, the portion other than the flow path (channel) is etched during etching through KOH for increasing the surface area while using the DFR film, thereby preventing the weakening of the bonding density of the entire bonding surfaces and thus, the glass layer on the wafer. glass anodic bonding) enables more dense adhesion.

Finally, since the DFR film is coated and removed along with the formation of the micro channel on the wafer, it is possible to provide an excellent effect such as miniaturization of the reformer while improving the performance of the micro reformer using the wafer.

While the invention has been shown and described with respect to specific embodiments thereof, those skilled in the art can variously modify the invention without departing from the spirit and scope of the invention as set forth in the claims below. And that it can be changed. Nevertheless, it will be clearly understood that all such modifications and variations are included within the scope of the present invention.

Claims (7)

In the reformer manufacturing method using a silicon wafer, Forming a flow path for fuel evaporation and hydrogen reforming on the wafer; A second step of forming a hot wire under the wafer; A third step of coating a first DFR film on the upper surface of the wafer and removing a DFR film of a flow path portion; A fourth step of coating heat treatment of the first catalyst layer on the flow path and the primary DFR film; A fifth step of removing portions other than the flow path of the first catalyst layer and the first DRF and coating a second DFR film; A sixth step of coating and heat treating the second catalyst layer on the first catalyst layer and the second DFR film; A seventh step of removing portions other than the flow path of the second catalyst layer and the second DFR film; And, An eighth step of bonding a glass layer on the lower surface of the wafer; Reformer manufacturing method comprising a. The method of claim 1, wherein a protective film for protecting the surface of the wafer is deposited by CVD before the first step. The method of claim 1, wherein the flow path of the first step is formed by etching a wafer using an inductively coupled plasma (ICP) method after application, exposure, and etching of PR. The method of claim 1, wherein the hot wire of the second step is platinum is deposited by sputtering method through the application, exposure and etching of PR in the cavity (etched) with the etching solution in the lower part of the wafer, after which the PR other than the hot wire is removed Reformer manufacturing method characterized in that. The method of claim 1, wherein after the first step, an insulating layer is formed on the wafer surface by CVD. The method of claim 1, wherein the first and second DFR films are coated with a roller coater and removed by acetone application and pure water washing. The Al ₂ O ₃ spray method according to claim 1, wherein the first catalyst layer of the fourth stage is one of CuO or ZnO which is spray coated thereon in the next sixth stage. Reformer manufacturing method characterized in that the coating.

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