JPH08290911A - Continuous refining method of quartz powder - Google Patents

Abstract

PURPOSE: To obtain inexpensively high purity quartz powders with a good productivity by a process in which a rotating cylindrical quartz chamber is divided into at least three chambers and raw quartz is continuously supplied to a preliminary heating chamber and preheated and then the quartz powders are moved to bring into contact with a chlorine-contained atmospheric gas to refine and sent to a gas separation chamber.

CONSTITUTION: A preheating chamber, a reaction chamber and glass separation chamber are separated with partition boards having a opening. The opening rate of the opening is elected in the range of 10 to 40%. The preheating temperature is maintained higher than 800°C, a reaction temperature 1,000 to 1,300°C and the temperature of the gas separation chamber higher than 800°C. The chlorine-contained atmospheric gas is preferably a mixed gas comprising a ratio of hydrogen chloride gas to chlorine gas 2:1 to 20:1. Impurities in the refined quartz powders and Na concentration lower than 10 ppb, K concentration lower than 150 ppb, Fe concentration lower than 70 ppb, Cu concentration lower than 0.3 ppb, Ni concentration lower than 0.3 ppb, Cr concentration lower than 0.5 ppb. Throughput of this process is 1 to 20 kg/h.

COPYRIGHT: (C)1996,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an improved method for refining silica powder, more specifically, silica powder used as a raw material for silica glass containers and jigs used in the semiconductor industry, and as silica filler for plastic packages. The present invention relates to a method for continuously purifying to high purity.

[0002]

2. Description of the Related Art Conventionally, quartz powder, especially natural quartz powder, has been used as a silica glass raw material for forming a silica glass container or a jig or as a silica filler raw material for plastic packages such as IC and LSI. However,
The quartz powder contains various impurities, which are purified because they adversely affect semiconductor products. For example, US Pat. Powder is mixed with chlorine-containing atmosphere gas 7
The method of contacting and purifying at a temperature of 00 to 1300 ° C.
Further, Japanese Patent Application Laid-Open No. 48-69794 discloses a method of refining by contacting quartz powder at a temperature of 700 to 1300 ° C. in an atmosphere containing chlorine or chlorine.

Although the purification method of the above-mentioned US Pat. No. 4,956,059 is a purification method for purifying natural quartz to a high purity, the purification step is a batch type reaction and the reaction of the purification apparatus. Since the tube was energized, the production cost was high and it was not possible to inexpensively produce high-purity quartz powder. Further, in the purification method disclosed in Japanese Patent Laid-Open No. 48-69794, purification of alkali metal elements, alkaline earth elements, transition metal elements, radioactive elements and the like contained in natural quartz powder, particularly alkaline earth metal elements and transition metals The elements were not sufficiently purified and did not satisfy the purity required in the recent semiconductor industry.

[0004]

In view of the current situation,
As a result of intensive studies, the present inventors have established at least three chambers in a rotating cylindrical quartz glass tube, which are a preheating chamber, a reaction chamber, and a gas desorption chamber, and the raw material quartz powder is rolled into each chamber. The inventors have found that high-purity quartz powder, in particular, quartz powder in which alkali metal elements, alkaline earth metal elements, and transition metal elements are highly purified, can be manufactured at low cost, thus completing the present invention. Ie

An object of the present invention is to provide a continuous purification method of quartz powder for highly purifying impurities that adversely affect silicon wafers and the like.

Another object of the present invention is to provide a refining method for inexpensively producing high-purity quartz powder.

[0007]

According to the present invention to achieve the above object, in a method for continuously purifying quartz powder in a rotating cylindrical quartz glass tube, the rotating cylindrical quartz glass tube is divided into at least three chambers, As a preheating chamber, reaction chamber, and gas desorption chamber, the raw material quartz powder is continuously supplied to the preheating chamber and preheated, and then it is transferred to the reaction chamber and brought into contact with the chlorine-containing atmosphere gas to purify it, and then the gas. The present invention relates to a continuous refining method for quartz powder, characterized by rolling in a separation chamber.

The above-mentioned quartz powder means natural quartz, quartz, silica stone,
Also, it refers to quartz powder in which the synthesized quartz is pulverized and classified by a conventional method to adjust the particle size to a range of about 250 to 106 μm.
In the crushing of the quartz, heating may be performed to facilitate the crushing. If the particle size of the quartz powder is less than the above range, it is unsuitable for the production of excessively fine silica glass, and if it exceeds the above range, the purification treatment is not sufficiently performed, which is disadvantageous.

In the refining method of the present invention, quartz powder is continuously fed into a rotating cylindrical quartz glass tube (hereinafter referred to as a rotary kiln) and tumbled for refining. At least three chambers are provided inside the rotary kiln. Each of the chambers is divided into a preheating chamber, a reaction chamber, and a gas desorption chamber, and quartz powder as a raw material is rolled into each chamber. It is preferable that the chamber formed inside the rotary kiln, that is, the preheating chamber, the reaction chamber, and the gas desorption chamber be partitioned by a partition plate having an opening. The partition plate is made of quartz glass, and the opening portion provided therein has an opening ratio within the range of 10 to 40%, and the particle size of the raw material quartz powder,
Selected based on quality etc. In particular, in selecting the opening ratio of the opening of the partition plate between the reaction chamber and the gas desorption chamber, it is preferable to select the range in which the opening is substantially closed by the quartz powder that rolls during the refining process. . The substantially closed state means a state in which chlorine-containing atmosphere gas does not flow into the gas separation chamber from the free space of the opening. By maintaining such a closed state, re-adhesion of the chlorine-containing atmosphere gas to the purified quartz powder can be prevented, and the purification efficiency is improved.

The quartz powder as a raw material is successively rolled in the chamber by the rotary kiln rotating with an inclination. The rotation speed of the rotary kiln is 1 to 5 rpm, preferably 2
The inclination angle is selected to be 4 rpm, and the inclination angle is selected based on the processing amount and quality of the quartz powder.

A raw material inlet is provided in the preheating chamber in the rotary kiln, and a raw material powder supply pipe and a reaction gas exhaust pipe for exhausting the chlorine-containing atmosphere gas after the reaction are opened therein. A reaction gas supply pipe is opened in the reaction chamber to supply an atmosphere gas containing chlorine. Further, a desorption gas exhaust port and a quartz powder discharge port are opened in the gas desorption chamber to exhaust the desorption gas and to discharge purified quartz powder. A ventilating means is preferably connected to the desorbed gas exhaust pipe to promote desorption of gas.

The quartz powder introduced from the raw material powder supply pipe of the rotary kiln is heated to at least 800 ° C. in the preheating chamber and then transferred to the reaction chamber where the chlorine-containing atmosphere gas supplied from the reaction gas supply pipe is supplied. 1000-1300
It is contacted and purified in the temperature range of ℃. The purified quartz powder is transferred to a gas desorption chamber heated to preferably 800 ° C. or higher and lower than the reaction temperature, and the adsorbed gas is desorbed from the surface of the quartz powder and gradually cooled.

In the above purification method, if the temperature of the preheating chamber is lower than 800 ° C., the purification treatment in the reaction chamber is not suitably performed, and if the temperature of the reaction chamber is lower than 1000 ° C., the purification efficiency is poor and the desired purity is achieved. Can not do it. Further, if the temperature of the reaction chamber exceeds 1300 ° C., there arises a problem in the durability of the apparatus. Further, it is preferable that the chlorine-containing atmosphere gas introduced into the reaction chamber is previously heated to around the reaction temperature and then introduced. As a result, the quartz powder is not cooled and the purification efficiency does not decrease. The chlorine-containing atmosphere gas can be introduced by directly introducing the chlorine-containing atmosphere gas heated outside the rotary kiln, or by passing the reaction gas supply pipe through the gas desorption chamber and heating it in the gas desorption chamber. The method of doing is adopted.

As the chlorine-containing atmosphere gas used in the purification method of the present invention, a mixed gas of hydrogen chloride gas and chlorine gas, and a mixed gas obtained by further mixing the mixed gas with an inert gas such as nitrogen gas are used. It Particularly, a mixed gas of hydrogen chloride gas and chlorine gas is preferable, and the mixing ratio thereof is in the range of hydrogen chloride gas: chlorine gas = 2: 1 to 20: 1, preferably 4: 1 to 13: 1. If the mixing ratio of the mixed gas deviates from the above range, insufficient purification of alkali metal elements and transition metal elements will occur.

The processing amount by the purification method of the present invention is 1 to 20.
The optimum value is kg / hour, preferably 1 to 10 kg / hour.
If it is less than the above range, the productivity will be poor, and if it exceeds the above range, the purification of the alkali metal element will be slow.

Impurities in the quartz powder obtained by the purification method of the present invention have a sodium element concentration of 10 ppb or less,
Potassium element concentration is less than 150 ppb, iron element concentration is 7
0 ppb or less, copper element concentration 0.3 ppb or less, nickel element concentration 0.3 ppb or less, chromium element concentration 0.
It will be 5 ppb or less.

In the above-described purification method of the present invention, the purification step may be repeated a plurality of times in order to improve the purification efficiency, particularly the transition metal element purification efficiency. In the quartz powder thus purified, the alkali metal element and the transition metal element are preferably purified, and the alkaline earth metal element, which has been difficult to purify by the conventional purification method, is also sufficiently purified. You can

Examples are shown below to specifically illustrate the present invention, but the present invention is not limited thereto.

[0019]

【Example】

Example 1 A quartz glass partition kiln having an inner diameter of 100 mm and a length of 2000 mm was preheated by a quartz glass partition plate.
A reaction chamber chamber and a gas desorption chamber are formed, and a partition plate between the preheating chamber and the reaction chamber chamber has an opening with an opening ratio of 15%, and a partition plate between the reaction chamber chamber and the gas desorption chamber. An opening having an opening ratio of 35% was provided in the. Then, the quartz glass rotary kiln was installed with an inclination of about 4 °. Natural quartz powder having a particle size of 250 to 106 μm is continuously fed into the rotary kiln at a rate of about 1.5 kg / hour, and the natural quartz powder is heated to about 100 by a heater provided on the outer periphery of the rotary kiln.
It is heated to 0 ° C., tumbled in a reaction chamber and heated to about 1270 ° C., and a mixed gas of hydrogen chloride gas and chlorine gas having a mixing ratio of 1: 0.075 l / min (13:
The gas was brought into contact with the gas of 1) to carry out a purification treatment. The purified quartz powder is rolled into a gas release chamber kept at 800 ° C,
The halogen element-containing atmosphere gas adhering to the surface of the quartz powder was desorbed while being gradually cooled. A ventilating means was connected to the desorption gas exhaust pipe opening to the gas desorption chamber of the quartz glass rotary kiln in order to promote gas desorption.

The above purification treatment was continuously carried out for 2 hours to obtain about 10 kg of high-purity quartz powder. When the impurities in the obtained quartz powder were analyzed, it was as shown in Table 1.

Example 2 The ratio of hydrogen chloride gas to chlorine gas was 1: 0.25 l / min.
Natural quartz powder was purified in the same manner as in Example 1 except that the mixing ratio was 4: 1. The amount of impurities in the obtained natural quartz powder was as shown in Table 1.

Comparative Example 1 Natural quartz powder was purified in the same manner as in Example 1 except that the temperature of the preheating chamber was 500 ° C. The impurities in the obtained natural quartz powder were analyzed and the results were as shown in Table 1.

Comparative Example 2 Natural quartz powder was purified in the same manner as in Example 1 except that the heating temperature in the reaction chamber was set to 900 ° C. The impurities in the obtained natural quartz powder were analyzed and the results were as shown in Table 1.

Comparative Example 3 Natural quartz powder was purified in the same manner as in Example 1 except that the volume ratio of hydrogen chloride gas and chlorine gas was 23: 1. When the impurities in the obtained natural quartz powder were analyzed, Table 1
It was as shown in.

[0024]

[Table 1]

As shown in Table 1 above, sodium, potassium and transition metal elements are preferably purified by the purification method of the present invention. Further, purification of alkaline earth metal elements such as magnesium and calcium has been carried out.

[0026]

According to the refining method of the present invention, impurities in quartz powder, particularly alkali metal elements such as sodium and potassium in natural quartz powder and transition metal elements such as iron, copper, chromium and nickel are preferably purified. And magnesium,
Alkaline earth metal elements such as calcium are also sufficiently purified. In addition, since the purification method is continuous, it is an industrially advantageous purification method because it has good productivity and can inexpensively obtain high-purity quartz powder.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Werner Pont, Republic of the Federal Republic of Germany 63486 Burchikebel Gesivister Schol Citrase 20 (72) Inventor Tatsuhiro Sato 2-13-60 Kitafu, Takefu City, Fukui Prefecture Shin-Etsuishi Ei Share Company Takefu Factory (72) Inventor Hiroyuki Watanabe 2-13-60 Kitafu, Takefu City, Fukui Prefecture Shin-Etsuishi Ei Co., Ltd. Takefu Factory

Claims (9)

[Claims] 1. A method for continuously purifying quartz powder in a rotating cylindrical quartz glass tube, wherein the rotating cylindrical quartz glass tube is divided into at least three chambers, a preheating chamber, a reaction chamber, and a gas desorption chamber. In addition, the raw material quartz powder is continuously supplied to the preheating chamber and preheated, and then it is tumbled into the reaction chamber and brought into contact with the chlorine-containing atmosphere gas for purification, and then tumbled into the gas desorption chamber. Continuous purification method for quartz powder. 2. The method for continuously purifying quartz powder according to claim 1, wherein the preheating chamber, the reaction chamber, and the gas desorption chamber are chambers partitioned by a partition plate having an opening. 3. The method for continuously purifying quartz powder according to claim 2, wherein the opening of the partition plate is selected within a range of an opening ratio of 10 to 40%. 4. The method for continuously purifying quartz powder according to claim 1, wherein the preheating temperature is at least 800 ° C. and the reaction temperature is 1000 to 1300 ° C. 5. The continuous purification method for quartz powder according to claim 1, wherein the chlorine-containing atmosphere gas supplied to the reaction chamber is preheated. 6. The method for continuously purifying quartz powder according to claim 1, wherein the temperature of the gas desorption chamber is 800 ° C. or higher and lower than the reaction temperature. 7. The method for continuously purifying quartz powder according to claim 2, wherein the purified quartz powder substantially closes the opening of the partition plate between the reaction chamber and the gas desorption chamber. 8. The continuous purification method of quartz powder according to claim 1, wherein a ventilating means is connected to a desorbed gas exhaust pipe opening to the gas desorption chamber. 9. The method for purifying quartz powder according to claim 1, wherein the chlorine-containing atmosphere gas is a mixed gas composed of hydrogen chloride gas and chlorine gas in a ratio of 2: 1 to 20: 1.