JP2818054B2 - Water decomposing agent, method for decomposing and decomposing water on material surface using the same, method for decomposing and removing water in gas, and their devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the dissociation of water molecules and hydroxyl groups adsorbed on the surface of a solid material, or water molecules and hydroxyl groups contained in a gas, into hydrogen and oxygen, which are constituent atoms of the molecules. The present invention relates to a decomposing agent to be removed by the method, a method for decomposing and removing water molecules and hydroxyl groups using the decomposing agent, and a device therefor, and relates to a technology which is effective in various advanced technology fields represented by high vacuum technology or semiconductor technology.

[0002]

2. Description of the Related Art Vacuum technology has been extremely important as a basic technology that supports many technologies. Moreover, nuclear fusion, particle accelerators, space technology and other huge sciences as technologies supporting future human society and industry, research and development of superconducting materials,
Practical application of pressure range from ultra-high vacuum to ultra-high vacuum in the development of semiconductor technologies and processes aiming for high density, high integration and super lattice, and in the most advanced technology fields such as electronic equipment, light utilization technology and new material development Is considered an important and indispensable technical issue.

In general, when a high degree of vacuum is required or in the production of functional materials and devices such as semiconductor devices, the most important and decisive factors that hinder the degree of vacuum, materials and device grades are: It is a gas component adsorbed on the material surface of a vacuum device, and among them, it is particularly considered to be water having a strong adsorbing power and affinity for the material or a hydroxyl group (oxyhydro group) chemically bonded to the material surface. For this reason, the development of an efficient removal technique of the water adsorbed on the material surface is desired.

Gas components adsorbed on the surface of high vacuum equipment materials,
In particular, removal of adsorbed water has been a technically difficult task. For example, conventionally, a baking method of removing adsorbed components by heating, a pretreatment method of a material to smooth and clean the material surface by polishing, a plating or coating or a special surface treatment, etc. A method of deactivation, a method of cooling with liquid nitrogen to condense and condense water in the system to lower the vapor pressure, and many other material treatment methods have been developed and put into practical use. It has been.

Further, in the case of various functional materials typified by semiconductor elements such as LSIs, materials for manufacturing elements, and functionalization processing of elements, the surface state of the materials and elements has no adsorbed components. Keeping in a clean state is the most important and decisive influencing factor for its function expression. For this reason, LSI
In the device manufacturing process, many methods for reducing and removing adsorbed water have been studied and put to practical use with respect to the manufacturing equipment and process or the surface of the device itself.

The water molecules adsorbed on the surface of the material are firmly adsorbed on the surface of the material due to the strong van der Waals force. Therefore, it is extremely difficult to completely remove the water molecules even by heating. Even more, removing hydroxyl groups bound to the material surface requires heating to extremely high temperatures,
Its complete removal was almost impossible.

Furthermore, in recent years, aluminum alloys have been used as the main component material in these fields to reduce the weight and workability. However, this aluminum-based material forms a stable hydrated oxide film and a hydroxyl group on its surface, and It is difficult to remove not only hydroxyl groups but also adsorbed water, for example, because the baking temperature cannot be too high. More recently, in many industrial technology fields and especially in advanced technology fields, there is a strong demand for an environment with an extremely high degree of vacuum, that is, an environment such as an ultra-high vacuum or an ultra-high vacuum, and high density and high integration of semiconductor elements. . In such a situation, there are problems such as improvement of the degree of vacuum, improvement of the semiconductor process, time required to reach a target degree of vacuum, and cost for the purpose.

[0008]

However, the conventional water removal techniques listed above are all methods for removing adsorbed water with its water molecular structure, and therefore have extremely strong adsorption power and affinity for the material. However, in the case of water having the above, there is a problem in terms of removal efficiency and economy. It is extremely difficult to completely remove the moisture adsorbed on the material surface, or even the hydroxyl groups. For example, in order to completely remove the adsorbed moisture on the surface of an inorganic material such as a metal material by baking, the material must be 400 to
It is necessary to heat to 500 ° C. or higher. However, it is often difficult to remove adsorbed moisture in the case of a complicated and large-sized material or apparatus, or when baking cannot be performed due to the material or structure. Under these circumstances, as the demand for the improvement of the degree of vacuum increases, along with the sophistication of a high vacuum environment (ultra high vacuum degree) represented by particle accelerators and the enlargement of vacuum equipment, the conventional baking method and There is a demand for the development of a new moisture removal technology instead of the conventional moisture removal technology that requires a special surface treatment on the entire surface of the material.

[0009] It is an object of the present invention to provide a decomposing agent, a method and an apparatus capable of more efficiently removing water in response to the above-mentioned conventional demands.

[0010]

That is, in order to achieve the above object, the present invention firstly provides a gaseous water containing as a main component a substance which decomposes water molecules or oxyhydro groups into volatile substances at room temperature. Provide a decomposer. Second, a gaseous water decomposer mainly composed of a substance that decomposes water molecules or oxyhydro groups into volatile substances at room temperature is applied to the surface of a solid material, and the constituent atoms of water adsorbed on the surface of the solid material Disclosed is a method for decomposing and removing water adsorbed on a material surface, which comprises dissociating a bond between oxygen and hydrogen to decompose water and / or oxyhydro groups bonded to the material surface into volatile substances. Third, a gaseous water decomposer whose main component is a substance that decomposes water molecules or oxyhydro groups into volatile substances at room temperature is applied to the gas, and is a constituent atom of water present in the gas. Disclosed is a method for decomposing and removing water in a gas, which comprises dissociating a bond between oxygen and hydrogen to decompose water or an oxyhydro group in a gas into a volatile substance and remove the volatile substance.

Fourthly, a means for supplying a gaseous water decomposer mainly composed of a substance which decomposes water molecules or oxyhydro groups into volatile substances at room temperature to the surface of the solid material, and adsorbed on the surface of the material. Provided is a device for adsorbing and decomposing water on a material surface, comprising means for collecting and removing volatile substances decomposed and generated from water from the surface of a solid material. Fifth, means for supplying a gaseous water decomposer mainly containing a substance that decomposes water molecules or oxyhydro groups into volatile substances at room temperature into a closed space, and water adsorbed on the surface of the material. The present invention provides a device for decomposing and removing moisture in a gas, comprising means for collecting and removing volatile substances decomposed and generated from the same space from the same space. Sixth, means for passing a gas through a liquid water-decomposing agent mainly composed of a substance that decomposes a water molecule or an oxyhydro group into a volatile substance at room temperature, and is formed by a decomposition reaction between the water-decomposing agent and the gas. Means for removing and recovering volatile substances.

[0012]

When the decomposing agent is applied to a solid surface or a gas, water molecules adsorbed on the solid surface and oxygen and hydrogen constituting an oxyhydro group (hydroxyl group) are dissociated. The resulting reaction product is Since it is volatile, it can be removed at room temperature without leaving any residue on the material surface or in the gas.

[0013]

Next, the present invention will be described more specifically with reference to examples. The present invention provides a method of spraying a gaseous decomposing agent having a function of decomposing water molecules and oxyhydro groups onto a vacuum material or an element surface, or injecting the gaseous decomposing agent into a vacuum device or a manufacturing process, thereby adsorbing moisture (and a bond-type This is a technology that decomposes and removes (hydroxyl groups) at room temperature, and is an effective technology in terms of improvement of removal efficiency or workability as compared with conventional adsorption moisture removal technology.

As a water-decomposable decomposing agent, a chlorine-based silane compound as shown in Table 1 has its function. All of these have a high vapor pressure even if they are gaseous or liquid at room temperature, and the water splitting reaction thereby proceeds at room temperature.

[0015]

[Table 1] 名 Decomposer name Chemical formula FW mp (℃ ) Bp (℃) ─────────────────────────────────── chlorotrimethylsilane SiCl (CH ₃ ) ₃ 108.6 -40 57 Dimethylchlorosilane SiClH (CH ₃ ) ₂ 94.6 -111 36 Dichlorodimethylsilane SiCl ₂ (CH ₃ ) ₂ 129.1 -76 70.3 Trichloromethylsilane SiCl ₃ CH ₃ 149.5 -78 66.4 Tetrachlorosilane SiCl ₄ 169.9 -70 57 2,2-Dichlorofluorocarbon CCl ₂ (CH ₃ ) ₂ 113.0 -34.4 70.5 Diphorane B ₂ H ₆ 27.7 -166 -92.5 Phosphane (Carbonyl chloride) COCl ₂ 98.9 -128 7.5 ─────────── ────────────────────────

The water decomposition reaction of these substances is shown in the following formulas (1) to (4). The formula (1) shows the case of dichlorodimethylsilane in the chlorine-based silane compounds in Table 1. (CH ₃ ) ₂ SiCl ₂ + H ₂ O → [(CH ₃ ) ₂ SiO] + 2HCl ↑ (1) dimethyldichlorosilane silicon polymer (CH ₃ ) ₂ CCl ₂ + H ₂ O → (CH ₃ ) ₂ C = O ↑ + 2HCl ↑ ... (2) 2,2- dichloropropane acetone _{B 2 H 6 + H 2 O} → 2H 2 BO 3 + 6H 2 ↑ ... (3) diborane borate _{COCl 2 + H 2 O → CO} 2 ↑ + 2HCl ↑ ... (4) Phosgene carbon dioxide

These gaseous water decomposing agents are blown into high vacuum materials, equipment and manufacturing processes to decompose and remove moisture (and bonded hydroxyl groups on the material surfaces) strongly adsorbed on the surfaces of the materials. . This water splitting reaction proceeds quickly at normal temperature, and the efficiency of water splitting and removal is high.

For example, FIGS. 1 and 2 show the mechanism of decomposition and removal of water adsorbed on the material surface. As shown in these figures, when a water molecule comes into contact with dichloropropane or phosgene, the interatomic bond between oxygen and hydrogen in the water molecule structure is dissociated, and the water molecule is destroyed. According to dichloropropane or phosgene, the molecular structure of water that is physically and chemically strongly adsorbed on the surface of the material 1 is destroyed. As a result, the hydrogen atoms of water are converted into chlorides, and the oxygen atoms are converted into acetone or carbon dioxide, all of which are gasified and removed from the surface of the material 1. Further, the water splitting agent having the ability to chemically dissociate the interatomic bond between hydrogen and oxygen is also effective for oxyhydro groups (hydroxyl groups) which are chemically bonded to the surface of materials, elements and the like and stably exist. Thus, the oxyhydro group can be removed from the surface of the material 1 by the mechanism shown in FIG.

FIG. 4 shows an example of an apparatus for carrying out this method.
Shown in This device has a function of controlling the supply of a water splitting agent and a function of efficiently removing acidic and corrosive hydrogen chloride gas generated and volatilized after the water splitting reaction. The water decomposing agent A is supplied into the processing system 45 in which the target to be removed from the supply unit 43 is stored together with the purge gas supplied from the purge gas supply unit 42 and the water molecules are decomposed as described above. Is performed. The reaction product B is exhausted out of the system after harmful substances are removed through a harm removal trap 46 containing a solid alkali adsorbent and the like. Further, among the gas exhausted from the processing system 45, the water decomposing agent A is returned to the processing system 45 by the circulation pump 44 and is reused.

In the above water splitting reaction, (1)
Hydrogen chloride, which is corrosive to metallic materials, is generated as a decomposition product of the reaction of the formulas (2) and (4). This hydrogen chloride has a very low boiling point of −84.9 ° C. If it is not present (the adsorbed water which is a problem in this high vacuum environment is adsorbed on the material surface at the single molecule level and there is no moisture condensation), there is no corrosiveness to the material . However, in the case of a silane compound, the silicon polymer remains on the material surface after the water decomposition reaction proceeds, as shown in equation (1), which is the water decomposition reaction.
In the case of diborane of the formula (3), no hydrogen chloride is produced as a reaction product, but boric acid remains on the material surface after the water decomposition reaction. A chemical that leaves a non-volatile reaction product on the surface of a material due to the adsorption water decomposition reaction is not suitable for improving the degree of vacuum or treating the surface of a semiconductor element.

For the above reasons, water-decomposable gaseous chemicals suitable for the purpose of improving the degree of vacuum and treating the surface of semiconductor elements and the like are dichloropropane and phosgene represented by the formulas (2) and (4). With these chemicals, adsorbed moisture is decomposed and removed from the material surface without producing any residue on the material surface, and the material surface state becomes high vacuum and suitable for semiconductor devices.

Although the above description has been given of the decomposition and removal of water molecules adsorbed on the solid surface, the point of this point is that also in the case of decomposing water molecules contained in gas, the decomposition reaction of water molecules is performed on the solid surface. The other is exactly the same, except that it is performed in a gas. FIG. 5 shows an example of an apparatus suitable for decomposing and removing water molecules in a gas.

An inert gas a such as argon or nitrogen is blown into a container 57 filled with a liquid water-decomposing agent, and the water-decomposed agent c ′ vaporized together with these gases a passes through a cooling unit 52 to be adsorbed on a solid alkali. It is sent to the units 53, 53. In the drawing, “b” indicates the refrigerant supplied to the cooling unit 52. After the solid alkali is removed by the solid alkali adsorption units 53, 53, the water-decomposing agent c ′ passes through the liquid nitrogen trap 55 to remove water, and is dried in a processing system 56 such as a vacuum chamber. Sent. In this processing system, water in the gas is decomposed, and the generated volatile decomposition gas is exhausted to the outside of the system. This exhaust gas passes through the abatement trap as described above, and after harmful substances are removed,
Exhausted.

A gas is passed through a liquid water decomposer mainly composed of a substance that decomposes water molecules or oxyhydro groups into volatile substances at room temperature. At this time, a gas is produced by a decomposition reaction between the water decomposer and the gas. By removing and collecting the volatile substances, the moisture in the gas can be removed.

Next, a more specific embodiment of the present invention will be described. It should be noted that it is difficult to quantitatively evaluate the decomposition and removal rate of ordinary water (light water: H ₂ O) in order to confirm the decomposability of a trace amount of water adsorbed on the material surface. For this reason, the following implementations mainly use tritium water (HTO, T ₂
The effectiveness of the present invention was confirmed by evaluating the adsorption and removal behavior of water by measuring its radioactivity using O 2).

Example 1 In this example, the evaluation of the decomposition and removal of trace amounts of adsorbed water was performed using tritium, and among the four types of water decomposition reaction formulas shown in the above formulas (1) to (4). The reactivity of two hydrolyzing agents that did not leave any reaction product in any of dichloropropane and phosgene was confirmed, and the decomposition efficiency and the decomposition removal time were quantitatively evaluated. In addition,
Organic silane compounds were also tested for comparison. The result is shown in FIG. According to this result, the water-splitting efficiency of the three kinds of chemicals, particularly dimethyldichlorosilane (DMS), phosgene (COCl ₂ ) and dichloropropane (DCP), is very good, and the water adsorbed on the material surface can be completely absorbed in a very short time Can be removed.

Example 2 In this example, after the reaction between the water adsorbed on the material surface and the water decomposing agent, the persistence of the reaction product on the material surface and the chemical species produced were investigated. FIG. 7 shows the results of the surface measurement. As a result, in the case of the organic silane compound, the silicon polymer-based substance remains on the material surface in any case, but no residue is observed with respect to dichloropropane and phosgene. This is considered that the reaction product volatilized from the material surface as shown in the above-mentioned water decomposition reaction formulas (2) and (4).

Embodiment 3 In this embodiment, as a specific application example of the method and apparatus for decomposing and removing water molecules in gas according to the present invention, the effectiveness of improving the degree of vacuum in a vacuum chamber was evaluated.
Dichloropropane and phosgene, which have no residual after the reaction, and dimethyldichlorosilane, an organic silane-based compound having a residual, were used as the water splitting agents, respectively, and a baking method was also tested. The result is shown in FIG. Dichloropropane and phosgene treated at room temperature have an effect of improving the degree of vacuum which is almost equivalent to that of baking (200 ° C), while dimethyldichlorosilane is inferior in reaching the degree of vacuum compared to the case of no treatment. Was. From these results, it was confirmed that dichloropropane and phosgene having no surface residual effect were effective in improving the degree of vacuum. FIG. 9 shows a similar test result.

[0029]

According to the present invention as described above, a trace amount of water firmly adsorbed on the surface of a material can be efficiently decomposed, and the decomposed hydrogen atoms and oxygen atoms can be completely converted into a gaseous compound. Can be removed. It is extremely effective to apply this moisture decomposition and removal technique to materials, devices, semiconductor element materials and manufacturing processes for creating a high vacuum state.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a decomposition mechanism of water molecules adsorbed on a material surface when phosgene is used as a water-decomposing agent.

FIG. 2 is a conceptual diagram showing a decomposition mechanism of water molecules adsorbed on a material surface when 2,2-dichloropropane is used as a water-decomposing agent.

FIG. 3 is a conceptual diagram showing a decomposition mechanism of an oxyhydro group on a material surface when phosgene and 2,2-dichloropropane are used as a water-splitting agent.

FIG. 4 shows decomposition of water molecules on a material surface according to an embodiment of the present invention;
It is a system diagram showing a removal device.

FIG. 5 is a system diagram showing an apparatus for decomposing and removing water molecules in gas according to an embodiment of the present invention.

FIG. 6 is a graph showing a relationship between a water decomposition gas treatment time and a water decomposition rate in an evaluation test for decomposing and removing trace amounts of adsorbed water.

FIG. 7 is a chart showing the results of surface measurements of the persistence of the reaction product on the material surface and the chemical species produced after the reaction between the water adsorbed on the material surface and the water decomposing agent.

FIG. 8 is a graph showing the relationship between the suction time and the ultimate degree of vacuum when the method for decomposing and removing water molecules in a gas according to the present invention is applied to a vacuum chamber and then vacuum-evacuating the chamber together with a comparative example. .

FIG. 9 is a graph showing the relationship between the suction time and the ultimate degree of vacuum when the chamber is subjected to vacuum suction after applying the method for decomposing and removing water molecules in gas of the present invention to a vacuum chamber, together with a comparative example. .

[Explanation of symbols]

 Reference Signs List 1 material 42 purge gas supply unit 43 water decomposition chemical supply unit 45 treatment system 46 abatement trap 44 circulation pump 57 water decomposition chemical container 52 cooling unit 53 solid alkali adsorption unit 55 liquid nitrogen trap 56 processing system 57 water decomposition chemical container

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C09K 3/18 B08B 3/08 C01B 7/01 H01L 21/304 CA (STN) WPI / L (QUESTEL)

Claims (11)

(57) [Claims] 1. A water decomposer comprising, as a main component, a substance which decomposes water molecules or oxyhydro groups into volatile substances at room temperature selected from the group consisting of chlorine-based silane compounds, 2,2-dichloropropane and diborane. 2. The water splitting agent according to claim 1, wherein the water splitting agent is 2,2-dichloropropane or diborane. 3. Water splitting mainly comprising a substance which decomposes a water molecule or an oxyhydro group into a volatile substance at room temperature selected from the group consisting of a chlorine-based silane compound, 2,2-dichloropropane, phosgene and diborane. The agent is applied to the surface of a solid material, dissociating the bonds between oxygen and hydrogen, which are constituent atoms of the water adsorbed on the surface of the material, and decomposing the adsorbed water on the material surface or oxyhydro groups bonded to the material surface into volatile substances And removing the material surface by adsorption. 4. The water-splitting agent is 2,2-dichloropropane,
4. The method according to claim 3, wherein the material is phosgene or diborane. 5. Water splitting mainly comprising a substance which decomposes a water molecule or an oxyhydro group into a volatile substance at room temperature selected from the group consisting of a chlorinated silane compound, 2,2-dichloropropane, phosgene and diborane. Applying the agent in a gas, dissociating the bond between oxygen and hydrogen, which are constituent atoms of water in the gas, decomposes water or oxyhydro groups in the gas into volatile substances and removes them. Method for decomposing and removing moisture in gas. 6. The water-decomposing agent is 2,2-dichloropropane,
The method for decomposing and removing water in a gas according to claim 5, which is phosgene or diborane. 7. Water splitting mainly comprising a substance which decomposes a water molecule or an oxyhydro group into a volatile substance at room temperature selected from the group consisting of a chlorinated silane compound, 2,2-dichloropropane, phosgene and diborane. A device for supplying an agent to a surface of a solid material, and a device for recovering and removing volatile substances decomposed and generated from water adsorbed on the surface of the material from the surface of the solid material, wherein . 8. The water-splitting agent is 2,2-dichloropropane,
8. The apparatus according to claim 7, wherein the apparatus is phosgene or diborane. 9. A water decomposer comprising a substance which decomposes a water molecule or an oxyhydro group into a volatile substance at room temperature selected from the group consisting of a chlorine-based silane compound, 2,2-dichloropropane and diborane. An apparatus for decomposing and removing moisture in a gas, comprising: means for supplying into a closed space; and means for recovering and removing from the space a volatile substance decomposed and generated from water adsorbed on the surface of the material. 10. The apparatus according to claim 9, wherein the water decomposing agent is 2,2-dichloropropane or diborane. 11. Water splitting mainly comprising a substance which decomposes water molecules or oxyhydro groups into volatile substances at room temperature selected from the group consisting of chlorine-based silane compounds, 2,2-dichloropropane, phosgene and diborane. An apparatus for decomposing and decomposing water in a gas, comprising: means for passing a gas through the agent; and means for removing and recovering volatile substances generated by a decomposition reaction between the water decomposing agent and the gas.