Patent Application
20110094872
The present invention relates to a method for producing of electronic grade reagents, in particular, it relates to a method for producing of ultra-clean and high-purity electronic grade isopropanol and hydrochloric acid.
The ultra-clean and high-purity reagents (also called Process Chemicals or Wet Chemicals) are the important and basic materials in the producing of the Very Large-Scale Integration (VLSI). Both the ultra-clean and high-purity electronic grade isopropanol and hydrochloric acid are very important and extensively used in producing of semiconductor and cleaning or corrosion during the assemblage of very large-scale integration etc.
Because of the rapid development of the IT technology, the purity requirement of the Process Chemicals is higher and higher. Particularly, with the integrated circuit's development, it is trended to miniaturization and high speed processing, the requirement of the purity is more critical than before. The content of single cation of the electronic grade hydrochloric acid or isopropanol turns into the ppb level from the ppm level, and correspondingly, the standard of the electronic grade hydrochloric acid and isopropanol turns into SEMI-C8 or SEMI-C12 from SEMI-C1 and SEMI-C7 (The SEMI-C is the chemical standard published by Semiconductor Equipment and Material International).
The regular production of the liquid Process Chemicals such as hydrochloric acid and isopropanol is sub-boiling distillation that uses the thermal radiation to hold the liquid phase temperature lower than boiling point and then evaporating and condensing to production of reagents, or rectification. But there is not mature technology for large-scale sub-boiling distillation production now, and the impurity's concentration of the electronic grade hydrochloric acid and isopropanol produced with regular rectification is high.
“PURE AND APPLIED CHEMISTRY” (1986, (10): 1412˜1418) disclosed a method for the production of ultra-clean and high-purity isopropanol. Adding CaO or Mg powder to reflux with iodine as activator, and then multiply rectifying to get the product of 99.4% and the moisture content of which is 600 ppm. However, the moisture content of the isopropanol produced through this method is too high.
Bin Zhu etc. reported a method for producing of electronic grade isopropanol in “Continuous Production of Electronic Grade Isopropanol from Technical Grade Isopropanol” (NATURAL GAS CHEMICAL INDUSTRY, 2009, 34 (2): 67). The continuous production of electronic grade isopropanol is realized through the combination of sub-boiling rectification and batch rectification. The product is in conformity with the CEMI-C8 standard, but the yield is reduced.
Chinese patent No. CN101362675A disclosed a method for the production of ultra-clean and high-purity isopropanol. Industrial grade isopropanol is purified through using four-stage rectification. The method of multistage rectification is high risk and heavy energy consumption.
Chinese patent No. CN1644487A disclosed a device with which the ultra-clean and high-purity hydrochloric acid can be produced with low temperature evaporation. The hydrochloride passes two-stage washing columns and bubbling columns, and it is absorbed by conductivity water in absorption tower, then evaporated at low temperature, and finely filtered to produce electronic grade hydrochloric acid. We can see that the equipments used in this invention are complicated.
Chinese patent No. CN1326766C disclosed a method for the producing of electronic grade hydrochloric acid. The hydrochloride acid produced can be used only as MOS grade or BV-III standard reagent in production of VLSI because of its limited purity.
The present invention provides a method for producing of ultra-clean and high-purity reagents with industrial grade hydrochloric acid or isopropanol as crude material. The hydrochloric acid or isopropanol up to SEMI-C8 or SEMI-C12 standard is produced with high yield and stabilize quality by the combination of the overheated steam, a microporous membrane filtration and the rectification. And the present invention overcomes the defects of high impurity content brought by traditional methods.
The method for producing of ultra-clean and high-purity electronic grade reagents includes the following steps:
Step 1, under the room temperature, the industrial grade isopropanol or hydrochloric acid is chemically pretreated and filtered; and collect colature;
Step 2, rectifying the colature and heating the steam to turns into overheated steam during the rectification, and then filtering the overheated steam through the microporous membrane;
Step 3, condensing the overheated steam, secondarily filtering the fraction collected through the microporous membrane, and controlling the number of solid particle to get the ultra-clean and High-purity isopropanol or hydrochloric acid.
The aperture of the microporous membrane, which is usually 0.1˜0.5 μm, can be determined according to the content of the impurity, and the microporous membrane can be composed of membrane and supporting frame both made of perfluoro-polymer.
The temperature of the overheated steam is unnecessary to be too high, and 2˜10° C. higher than the temperature of the steam in the rectifying column is enough.
It would be better to control the flow rate of the steam being 0.5˜1.5 m/s during the rectification.
An embodiment of the present invention includes following steps:
Step 1, adding the dearsenical agent to industrial grade hydrochloric acid, reacting 0.5˜1.5 hours to remove arsenic; filtering the hydrochloric acid and collecting the colature;
Step 2, under the temperature of 115˜116° C. in the top part of the rectifying column, atmospherically rectifying the colature with the flow rate 0.5˜1.5 meter/second in the column, and heating the steam to 118˜120° C. and turning into overheated steam during the rectification; then filtering the overheated steam through the microporous membrane of 0.1 μm aperture;
Step 3, condensing the overheated steam and collecting the fraction, and secondarily filtering the fraction through the microporous membrane.
The optimized dearsenical agent used is hydrazine hydrate of 40% mass concentration.
The optimized weight ratio between the hydrazine hydrate and the industrial grade hydrochloric acid is 5˜8:100.
Another embodiment of the present invention includes following steps:
Step 1, adding the dehydrant to the industrial grade isopropanol to react 0.5˜1.5 hours, filtering the isopropanol and collecting the colature;
Step 2, under the temperature of 82˜83° C. in the top part of the rectifying column, atmospherically rectifying the colature with the flow rate 0.5˜1.5 m/s in the column, and heating the steam to 84˜86° C. and turning into overheated steam during the rectification; then filtering the overheated steam through the microporous membrane with 0.1 μm aperture;
Step 3, condensing the overheated steam and collecting the fraction, and secondarily filtering the fraction through the microporous membrane.
The optimized dehydrant used is the CaCl2.
The optimized weight ratio between the CaCl2 and the industrial grade isopropanol is 3˜5:100.
In the above methods, the caskets and pipe walls contact with the isopropanol or hydrochloric acid preferably is made of the high-purity quartz or perfluoro-polymer. And the reservoirs preferably are made of perfluoro-polymer.
The ultra-clean and high-purity isopropanol produced, which purity is higher than 99.80%, the content of single cation in which is lower than 0.1 ppb, and the content of the particulates of ≧0.2 μm in which is lower than 5 pcs/ml, is in conformity with the SEMI-C12 standard.
The ultra-clean and high-purity hydrochloric acid produced, which purity is qualified, the content of single cation in which is lower than 1.0 ppb, and the content of the particulates of ≧0.5 μm in which is lower than 10 pcs/ml, is in conformity with the SEMI-C8 standard.
Overheated steam is involved in the method of the present invention. The steam and priming in the top half of rectifying column is heated to higher temperature than the boiling point of the feed liquor to come into being overheated steam, and the priming is eliminated and the steam and solid particulates made by ions persist only. The particulates and ions can be removed by twice filtrations. So the present invention overcomes the defect of high impurity content brought by traditional methods. The yield increases 0.5˜1 time, and the steam is cut per consumption in more than half. And the method is applicable for large-scale continuous production.
A better understanding of the present invention is obtained when the following non-limiting detailed description is considered with rectifying column as example in conjunction with
Step 1: under the normal temperature, industrial hydrochloric acid or isopropanol and pretreated agents such as dehydrant, dearsenical agent, oxidant or reductant are fed into the pretreatment reactor to pretreatment reaction to remove the maximum impurity and increase purity.
Filtering the crude material and collecting the colature.
Step 2: Rectifying the colature in the rectifying column with 0.5˜1.5 m/s flow rate of the steam.
There is a heater in the rectifying column to heat the steam during the rectification to turn into the overheated steam. And there is a microporous membrane filter in the top half of rectifying column to filter the overheated steam.
The most important part of the microporous membrane filter is the microporous membrane that formed by a membrane and a supporting frame, both of them are made of perfluoro-polymer that is the polymer all which hydrogen atoms link with carbon atoms are replaced by fluorine atoms such as the polytetrafluoroethylene or the tetrafluoroethylene-hexaluoropropylene copolymer. The perfluoro-polymer can be used when producing almost all reagents because of its supernormal stability and wide range of usage temperature. And the aperture of the microporous membrane, usually is 0.1˜0.5 μm, can be determined according to the content of the impurity.
Because of some priming generated during rectification and some impurities interfused in the priming, there will be some impurities in the fraction. And the purity of the product will be low. The overheated steam can gasify the priming to remove the priming in the steam. However, the temperature of the overheated steam is unnecessary to be too high, and 2˜10° C. higher than the temperature of the steam in the rectifying column is enough. The reason is that the thermal energy will be wasted and the useful life of the membrane will be shortened if the temperature of the overheated steam is too high.
Step 3: Condensing the overheated steam passed the microporous membrane filter and collect fraction. The fraction is pumped into the secondary microporous membrane filter to remove the particulates. The product is stored in reservoir and the by-product generated during the rectification is stored in by-product recovery unit.
In the methods above, the caskets and pipe walls contact with isopropanol or hydrochloric acid preferably is made of high-purity quartz or perfluoro-polymer. And the reservoirs preferably are made of perfluoro-polymer.
The purity is detected through the following methods: Optical Colorimetry with Platinum-Cobalt Standard Solution is chosen as the standard color for chromaticity; Gas Chromatography is applied in the Analysis for the content of isopropanol or hydrochloride; Carl Fisher Method is applied for the water content; Gravimetric Analysis is used for the residue after evaporation; ICP-MS is applied for the cations; and Ion-exchange Chromatograph Analysis is used for the anions.
And the analytical instruments are list in table 1.
CaCl2 is added into industrial isopropanol of 99.0 wt % and reacts 0.5˜1 hours for dehydration. And the weight ratio between the CaCl2 and the industrial isopropanol is 3˜5:100. Then, filtering the isopropanol and collecting colature.
Rectifying the colature at the 82˜83° C. temperature of top part in rectifying column and the normal atmosphere with the 0.5 m/s flow rate of the steam. Heating the steam to turn into overheated steam of 84˜86° C. The overheated steam is filtered by the microporous membrane filter with 0.1 μm aperture and condensed to liquid to remove the particles impurities.
Filtering the fraction by the secondary microporous membrane filter to remove most and get ultra-clean and high-purity isopropanol. The purity of the product is 99.85%, and the content of single cation is lower than 0.1 ppb, the content of the particulates which is larger than 0.2 μm in diameter is lower than 5 pcs/ml, and the product is in conformity with the SEMI-C12 standard.
Adding CaCl2 into industrial isopropanol of 99.0 wt % to dehydration. Filtering the isopropanol and collecting the colature.
Rectifying the colature at the 82-83° C. temperature of top part in rectifying column and the normal atmosphere. The flow rate of the steam is controlled to be 1.0 m/s to increase the production rate and productivity. The steam is heated to turn into the overheated steam of 84˜86° C. The overheated steam is filtered by the microporous membrane filter of 0.1 μm aperture and condensed to liquid to remove the particles impurities.
The fraction is filtered by the secondary microporous membrane filter to remove most impurity and get the ultra-clean and high-purity isopropanol. The purity of the product is 99.89%, the content of single cation is lower than 0.1 ppb, the content of the particulates of ≧0.2 μm is lower than 5 pcs/ml, and the product is in conformity with the SEMI-C12 standard.
The analytical results of the purity are list in table 2.
Adding the hydrazine hydrate of 40% mass concentration into industrial hydrochloric acid of 30.0 wt % and reacting 0.5˜1 hours for dearsenization. And the weight ratio between the hydrazine hydrate and the industrial hydrochloric acid is 5˜8:100. Filtering the isopropanol and collecting colature.
Rectifying the colature at the 115˜116° C. temperature of top part in rectifying column and the normal atmosphere with the 0.5 m/s flow rate of the steam. Heating the steam to turn into overheated steam of 118˜120° C. The overheated steam is filtered by the microporous membrane filter of 0.1 μm aperture and condensed to liquid to remove the particles impurities.
The fraction is filtered by the secondary microporous membrane filter to remove most and get ultra-clean and high-purity hydrochloric acid. The content of the hydrochloride is 36.2%, the content of single cation is lower than 1.0 ppb, the content of the particulates ≧0.5 μm is 9 pcs/ml, and the product is in conformity with the SEMI-C8 standard.
The analytical results of the purity are list in table 2.
The description above is the illustrations of application and the reagents, equipments, or operation and detection not mentioned are the normal and routine ones in this field of technology.
It shall be understood that the description of the embodiments above is only the illustrations of application, and it does not limit the invention to the specific embodiments illustrated. Numerous other ways of carrying out the method provided by the present invention may be devised by the skilled in the art without departing from the scope of the invention, thus they are encompassed by the present invention. Therefore it should be understood that any identical change can be done without departing from the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| CN 201010282669.6 | Sep 2009 | CN | national |
