JPH06196464A - Manufacture of semiconductor cleaning diethyl carbonate - Google Patents

Abstract

PURPOSE:To obtain semiconductor cleaning diethyl carbonate by a method wherein chlorine-containing diethyl carbonate is cleaned with weak alkaline water solution, then cleaned with pure water until it grows neutral, and dehydrated. CONSTITUTION:Chlorine-containing diethyl carbonate is cleaned a few times with weak alkaline water solution, for instance, alkaline metal hydrogen carbonate such as sodium hydrogencarbonate. Diethyl carbonate is cleaned with pure water after it is cleaned with alkaline water solution. It is preferable that deionized pure water is used. Diethyl carbonate is cleaned with pure water a few times till it grows neutral, and diethyl carbonate is recovered. Diethyl carbonate is cleaned with pure water and dehydrated. In this case, dehydration means that water content and residual chlorine are removed from diethyl carbonate usually through adsorption. Diethyl carbonate is brought into contact with adsorbent to remove water content and residual chlorine from it. By this setup, semiconductor cleaning diethyl carbonate can be manufactured from marketing diethyl carbonate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing semiconductor cleaning diethyl carbonate from diethyl carbonate.

[0002]

2. Description of the Related Art Cleaning agents for semiconductors are indispensable for improving their reliability. Conventionally, chlorofluorocarbon has been used for cleaning semiconductors, but it has been found that chlorofluorocarbon does not decompose in the atmosphere, reaches the stratosphere and is decomposed by ultraviolet rays, and chlorine atoms generated at that time destroy the ozone layer.

For this reason, research and development have been conducted on alternatives to CFCs that do not cause pollution, but in reality, complete alternatives have not been obtained. Therefore, the present inventors have found that the above problem can be solved by using pure diethyl carbonate as a semiconductor cleaning agent.

Commercially available diethyl carbonate is usually produced by the reaction of phosgene with ethylene glycol, the reaction of ethylene oxide with carbon dioxide gas, etc., and usually contains chlorine. However, the use of chlorine-containing diethyl carbonate for cleaning semiconductors causes corrosion of the semiconductors.

[0005]

In order to solve this problem, the present invention performs a specific treatment on chlorine-containing diethyl carbonate so that chlorine is hardly contained or the semiconductor cleaning is not hindered. The present invention relates to a method for producing diethyl carbonate for cleaning semiconductors by reducing the content thereof.

That is, according to the present invention, a method for producing diethyl carbonate for semiconductor cleaning is characterized in that diethyl carbonate containing chlorine is washed with a weak alkaline aqueous solution, washed with pure water until neutral, and then dehydrated. Is.

In the present invention, chlorine-containing diethyl carbonate is washed with a weak alkaline aqueous solution. As the alkali of the weak alkaline aqueous solution used here, various kinds can be used as long as they are weak alkalis which do not decompose diethyl carbonate.

For example, an alkali metal hydrogen carbonate exemplified by sodium hydrogen carbonate is preferably used. The pH of the weak alkaline aqueous solution is preferably 7.1 to 9, particularly preferably 8 to 8.5. Washing with an alkaline aqueous solution is usually performed several times.

After washing with an alkaline aqueous solution, washing with pure water is performed. Deionized ionized water is preferable as pure water. The diethyl carbonate layer is recovered by repeating the washing several times until it becomes neutral.

After washing with pure water, dehydration is performed. The dehydration mentioned here removes water and residual chlorine, and is usually removed by adsorption. In this dehydration step, water is substantially removed and chlorine is reduced to 5 ppb or less.

The adsorbent used for adsorption and the means for adsorbing may be any one that does not decompose diethyl carbonate and can remove water and residual chlorine. For example, a treating agent containing ceramics or animal bones as an active ingredient, Method of contacting with an adsorbent exemplified by gel permeation chromatography (G
The method is performed by appropriately selecting from an adsorbent and an adsorbing means known per se such as a method using PC).

As the ceramics, for example, alumina,
There are various types such as silica / alumina and zeolite, which are appropriately selected in consideration of adsorption performance. Gel permeation chromatography (GPC) is also called non-aqueous gel chromatography, is exclusion chromatography using an organic solvent as a mobile phase, and is appropriately selected and used from various types.

The treatment agent containing animal bone powder as an active ingredient is obtained by mixing animal bone powder as an active ingredient with a binder and, if necessary, other additives, molding into granules or powder granules, drying and firing. It will be. As animal bone powder, bones that have been mostly discarded in the past, such as cattle, horses, and sheep, are mainly used as animal bone meal.

The raw bones of these animals are treated, for example, by cutting into a size that is easy to bake, boiling, firing and cooling. By the above-mentioned boiling step, most of the organic substances attached not only to the outside but also inside the pores can be separated and removed from the bone. Furthermore, the remaining organic matter can be completely removed by the above-mentioned firing step, and at the same time, the humidity (water content) in the bone is reduced to several% or less,
It is preferably reduced to almost 0%.

The bone is whitened and maintains the original tissue state with numerous pores. After cooling, the bone is crushed and powdered to a size of 20-200 mesh, particularly preferably 50-10.
0 Bone powder in the form of powder. Bone meal is alkaline, contains calcium (about 33% by weight) as a main component, and phosphorus (about 33% by weight).
16.7% by weight), etc., and countless micropores are continuously present inside and outside the particles.

The binder may be any one that functions as a binder for forming animal bone powder into granules or powder granules. For example, bentonite, acid clay, activated clay, kaolin clay, sericite, pyrophyllite, refractory clay. , Montmorillonite, etc. In addition to the binder, other fillers and additives may be added if necessary.

Considering the adsorption performance, the proportion of animal bone powder in the treatment agent is high in the proportion of animal bone powder, for example, 50 to 80% by weight of animal bone powder. The filtering agent is granular or powdery, and the size thereof is usually 2 to 30 mm, preferably 5 to 20 mm. In addition, various adsorbents can be used.

In the method of the present invention, the dehydrated diethyl carbonate has a reduced chlorine content and is dehydrated.

[0019]

EXAMPLE Diethyl carbonate was purified in the following order. 1. 1 liter of commercially available diethyl carbonate was extracted with 1 liter of 0.1% sodium hydrogen carbonate solution. 2.1. The above operation was repeated several times. 3.2. Pure water (deionized water) from the diethyl carbonate obtained in
Then, the mixture was extracted several times until it became neutral, and the diethyl carbonate layer was collected. 4.3. The diethyl carbonate obtained in Step 3 was added to a three-layer column (from top to bottom: A. sodium hydrogen carbonate (40/60 mesh),
B. Synthetic zeolite-based dehydrating agent (40/60 mesh), C.I. It was supplied to a synthetic zeolite-based dehydrating agent (pellet form) and repurified.

When a semiconductor cleaning agent test was conducted using the diethyl carbonate obtained by the above column operation, contaminants and unnecessary substances adhering to the surface of the wafer were washed and removed.
Rust due to chlorine and similar ions was not observed.

[0021]

According to the present invention, it is possible to produce diethyl carbonate for semiconductor cleaning from commercially available diethyl carbonate.
Diethyl carbonate for semiconductor cleaning obtained here has high solubility for contaminants, unwanted substances, etc. adhering to the surface of the wafer,
According to the present invention, the wafer can be suitably washed, because it has the advantages that it does not corrode the wafer, it is a non-CFC type, it does not destroy the ozone layer, and the like.

Claims (8)

[Claims] 1. A method for producing diethyl carbonate for semiconductor cleaning, which comprises washing diethyl carbonate containing chlorine with a weak alkaline aqueous solution, washing with pure water until neutral, and then dehydrating. 2. The method according to claim 1, wherein the weak alkaline aqueous solution is an aqueous solution of an alkali metal hydrogen carbonate. 3. The method according to claim 1, wherein the weak alkaline aqueous solution is an aqueous solution of sodium hydrogen carbonate. 4. The method according to claim 1, wherein the pure water is deionized water. 5. The method according to claim 1, wherein the dehydration removes water and residual chlorine by adsorption. 6. The method according to claim 5, wherein the adsorbent used for adsorption is ceramics. 7. The method according to claim 5, wherein the adsorption is carried out by contacting with a treatment agent containing animal bone as an active ingredient. 8. Adsorption by gel permeation chromatography (GP
The method according to claim 5, wherein C) is used.