JPS5954632A - Preparation of quartz glass powder - Google Patents

Abstract

PURPOSE:To prepare high-purity quartz glass powder inexpensively, by adding a silicate such as alkali metal silicate, etc. to a mineral acid at a specific pH, precipitating water-containing silicic acid, cleaning, drying and calcining the precipitate. CONSTITUTION:In a raw material powder for preparing a crucible to pull up single crystal of semiconductor, a silicate of an alkali metal or alkaline earth metal is added to a mineral acid at <=1.5pH, to precipitate water-containing silicic acid. Water-glass is advantageously used as the silicate, nitric acid is effective as the mineral acid, the lower limit of its pH is about 0.5, and practically, its concentration is properly about 1-4 normal. The precipitated water- containing silicate is cleaned, dried, and calcined at about 1,100-1,300 deg.C for about 30min-2hr, to give quartz glass powder.

Description

[Detailed description of the invention] The present invention uses cumulative raw materials with few resource limitations.

The present invention relates to a raw material powder for producing crucibles for pulling semiconductor single crystals, and a method for producing high-purity quartz glass powder necessary as a filler for a sealant in a large-scale semiconductor assembly with 48 circuits.

Traditionally, quartz glass powder was produced by crushing high-quality natural quartz (crystal), such as Brazilian raw stone, in a ball, mill, etc., but in recent years, due to the increasing demand and depletion of natural quartz, resource In addition to the constraints mentioned above, issues regarding purity have become more apparent when it comes to the intended use.

Although natural quartz is of good quality, it contains various heavy metals and impurities, and it is difficult to use as a crucible for pulling semiconductor single crystals due to the penetration of the M metal impurities. By lowering the electronic physical properties of the produced crystals, alpha (α) rays emitted from impurities can be used as fillers for encapsulants in ultra-LSI (large-scale integrated circuits). It is η that causes the error (″/7 error).

For this reason, high purity powder with low uranium content is required.
In particular, as a filler for VLSI encapsulant, a high axiality product with a uranium level of 1 ppb or less is required. There is a strong need for a method of manufacturing vines that provides high quality quartz glass powder at low cost.

The inventors of the present invention use silica stone, which is relatively abundant in nature, as a starting material, based on such a method.

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The so-called sol-glu method is used to make quartz glass elements, which are used for painting.゜We proposed a method for manufacturing quartz glass powder, but the silicate ester as a raw material has a high rating (and therefore the cost of the νμ product is still high, so the selection of raw materials that is ¥1+!; 111i and that, .

A new manufacturing method is required.　　　　.

Traditionally, a cheap source of Irika for construction tools is water glass (Ane-shu nato vum's water habit liquid), which is produced by neutralizing it with mineral acid. , desiccant, or adsorbent d-silicon gels are manufactured. If 10% of this silica gel powder is heated at high temperature, glass powder (high silicate glass) consisting mainly of silica gold will be produced, but this silica gel contains various impurities including sodium. l:I for pulling semiconductor single crystals
The silica gel is not suitable as a filler material, and furthermore, the silica gel contains about a few ppb of uranium, which is an alpha-ray emitter derived from one of the raw materials, and cannot be sufficiently removed by cleaning with an iron ore. , Half, , 4 Tamotoza - Integrated circuits, especially for ultra-LSI seals that require uranium levels of 1 ppb or less: , As a filler for agents■, Hayashi r - Efficiency class Q"M
'9 of M technology is the premise.

The present inventors have developed a method for producing high-purity r'ib silica gel powder 1 by removing harmful impurities such as sodium, uranium, etc., using water glass as a groove. A method of manufacturing high-purity quartz glass powder by firing it at high temperatures was developed.As a result of repeated research, the reaction between water glass and mineral acid was carried out under conditions of a specific range of hydrogen ion concentration. If this is done, a good ice-containing silicon precipitate will be formed in the solid-liquid separation electrode, and if it is washed for 1 minute and then dried, it will become 1 mm thick and will be difficult to remove. I'm so happy that I've lost a lot of weight in ♀ minutes.I found out that Rika is going to be revealed and I posted one J.
reached. That is, the gist of the present invention is that the reaction between an alkali or alkaline earth metal silicate and a mineral acid is carried out under conditions where the total hydrogen ion concentration is 1.5 or less, and the hydrated silica+
, W k A method for producing silica glass powder, which comprises precipitating, washing, drying, and firing the precipitate of silicic acid.

In addition to the above-mentioned water glass, the raw materials used in the present invention include alkali metals such as potassium silicate and calcium silicate, and alkaline earth metal silicates [4], but similar results can be obtained industrially. □Water glass 6 is produced in large quantities and is available for use. 1) The viscosity BT is relatively low and the silicic acid content is relatively high 2.
In addition, as mineral acids, hydrochloric acid or nitric acid, which is generally used in the production of silica gel, has the effect of removing uranium, and is effective depending on the application, but it is especially effective for ultra-LSI Nitric acid is effective for 1□ which requires a uranium content of 1'ppb or less, such as a filler for a sealant.

These acid concentrations of elic acid and C are not limited as long as the pH is maintained at 1.5 or more during the reaction for producing a long-term acid. However, if the silicate is too dilute, the amount of polyacid will inevitably decrease due to the equivalence ratio with the alkali metal or alkaline earth metal in the silicate. This is disadvantageous because it increases the capacity of the equipment, and in practice, a concentration of 1 to 4N is appropriate. Therefore, I will briefly explain this point. Conventional silica gel manufacturing and creation uses the following method. (1) While maintaining the silica yield, the use of mineral acids is reduced as much as possible, and water treatment is also possible. In order to reduce the amount of j= (medium oro), add mineral acid to the water glass up to the point of total neutralization.

(2) Instead of so-called precipitate (powder), add ore to the water glass to form a gel mass, turn it into a gel via the sol, and divide the resulting gel into an appropriate size. Cut into pieces and wash after drying or before drying.

However, both methods lead to co-precipitation of uranium contained in water glass.

On the other hand, in the present invention, water glass is injected into mineral acid to completely generate hydrous silicic acid at low pH.
Precipitated (powdered) silica gold with very little uranium contamination.

In addition, as a manufacturing method for precipitated (wet) silica powder.

Calcium in water glass □ Um J: M”k Kakente 2 Kei #
Selected calcium iA:, produces lees, mother liquor gold content 14Lξ
Apply mineral acid to this and cuff 9. One: There is also a square crystal which is molten and has 'carbohydrate-containing acid precipitate', but it has not yet been invented.
There are many sea urchins ~ pr of old calcium j volume IB for the purpose of removal
(There is no flJ, it's t1m.) Next, I will explain in detail about the uninvented disease and 6e (2). is the reaction mother liquor core, (1.5 Ja '!' It
The Ci difference is 9 degrees, and the Alka IJ 'Q group to Al difference is 1'1. 1 vote for 1 and 3) child type +F1
'e'fr While stirring, pour all of the No. 2 water glass into the nuclear nitric acid to generate hydrated silicic acid ``71'' h ''6
``Q(□, I)H of the reaction mother liquor exceeds 5 and 14 points, stop the injection of the glass, and move on to the next step. After reacting the powder of lucium silicate, 9 mouths of the mother liquor □ was added to the calculated amount of 24' regular acid without exceeding 1.5 t'ixJ''□□E□! Stir 5 times while heating. Then, □gal□shiuhiro was eluted from the siliceous calcium.

There is also a method of making silicic acid M and books etc. □Desk: □□-ko”
t"r Houyou Palace water silicate sludge □ production reaction)", if it is carried out in the pH range that exceeds 5, then the uranium vertical Although it is possible to remove the power level and the cleaning VC rise, a sufficient reduction effect cannot be obtained.
As the pH of the mother liquor decreases, the amount of uranium in the hydrous silicic acid produced decreases, and at pH 1.5 or lower, it contains gellan.
Since the concentration can be reduced to below the ppb level, the precipitate-forming reaction of hydrated silicic acid, which is carried out by Honko Meikan, must be carried out at pH 1, 5'JV, -F. - During such a reaction, 'p'HIC-induced Ji'A'
The cause of the fluctuation in the uranium content in Honei silicic acid is not clear. If the iH region is only the adsorption of □ uranium in hydrous silicic acid, then the iH region will be the result! In addition, uranium □ is incorporated into the network of the hydrous silicic acid precipitate □, which becomes immobilized and cannot be removed even by pickling.

As the pH decreases, the strength of the nitric acid increases, increasing the rate at which uranium is dissolved in the solution, and especially under strong acidity with a K pH of 1.5 or less, hydrated silicic acid is precipitated. It is presumed that this is due to the fact that the amount of pen's contamination falls below the p and pb levels. Mineral acids other than the steel layer.

For example, sulfur, salt, etc. are also effective based on pH reduction (although they are effective, they are inferior to nitric acid in dissolving nitrates and sulfur, so furan's effect on the water content and diaphragm produced) It is thought that the contamination rate will increase.2.The lower limit of the pH during the reaction to produce hydrated silicic acid is not particularly limited, but if it is too low, the burden of disposing of the waste liquid as rIi strongly acidic reaction residual liquid may increase. This is not desirable as it increases the
K'tl:, It is desirable to keep bI,' ・
・ ・After the generated hydrated silicic acid settles, most of the supernatant liquid is discharged to a wastewater treatment system, or P
The 4'fc line is separated from most of the reaction mother liquor and added to the first washing step.

(2) Washing step In this step, most of the water-containing water separated from the reaction mother liquor
The phosphoric acid precipitate* is purified to remove the adhering and remaining reaction mother liquor and to maintain purity. This cleaning button uses deionized water or distilled water to maintain purity.
At the beginning of p operation, the cough water-containing acid precipitate should be attended to and the remaining...
Unwanted materials such as clans that combine in the mother liquor cause an increase in pu.
It is itchy because it may be adsorbed to hydrosilicic acid - pH
After rinsing with an acid of 1.5 or higher, it is desirable to thoroughly rinse with water.The degree of cleaning depends on the intended use of the product, but the It can be managed by electrical and electrical conductivity.

The washed hydrated silicic acid is separated by I/I filtration or the like, and then transferred to the next drying step.

(3) Drying type.

- In this step, the core hydrated silicic acid TI'i is dried after washing.

It is called meso-yuru silica gel. After drying, agglomeration may occur between the precipitated particles, forming a lump, but this can be removed by simple operations such as crushing.

・(4)・“Completion process In this step, the powdered silica gel that has been dried to form a 1→1 state is made into a dense 7-glass powder by firing.
The degree is that Shiri Kaguru-like, it's the manufacturing of the end! 'It depends on the history, but now it takes more than 1100°C. However, 130f no 0
Between particles at a temperature IW of 0 or more? In order to avoid troublesome operations such as grinding and re-grinding, it becomes like this.

``Contact'' between particles, dispersion, tower, Tsumugi! It is advisable to burn the candle at a temperature of 13°C or less. /:C:M, the firing time depends on the premature birth, but the firing time is 30 minutes to 112 hours at an axis temperature of 1100°C or higher and 1300°C.

The present invention will be explained in more detail by taking the example of the present invention as an example, but the gist of the present invention is determined by the following 4/la example. It's 1st best.
Processing amount 1 Dimethylpentene beaker (,2-Qlj' KL
), add 3N nitric acid (special grade reagent) 1e, and open the Teflon-coated impeller mold! While stirring, 400 ml of No. 3 water glass was slowly poured into the mixture, and the precipitate was completely removed.The pH at night was 0.6 and 1 liter.

After removing the supernatant, remove most of the mother liquor through e-filtering.

Next, return the 7i-cake to the original beaker, add 0.1N (+iJ1.5 form, , /ILI), repulp the cake, remove the upper 11tJ, add water to this pulp. After adding 1e and stirring, remove the supernatant liquid and repeat the decantation j* + □e gold twice, then dry the same) with only Makibo water 1'r and repeat 7 times in total. 〃”
We discussed it.

,, 1 kite, was it? 4 hours □ 30 OJ of water with the cake
W After injecting gold, drain all lines I good, 0 open 12
0. . Dry at C for one day and night to obtain approximately 120y of silica gel powder.
This silica gel lumber was placed in an opaque quartz glass bow HC and fired for 2 hours at 1100°C in 1'txtd' to obtain a fired powder of 1039. The specific gravity of this fired powder was 2. .195. The sin content was 99.94 or more, and the X-ray diffraction diagram 9 did not show a peak with crystals tn, so it was clear that 1 quartz glass powder and t'j 2 -C were present. The yield is better than 95%. As a result of the analysis, sodium content was 0.8ppmm, and uranium-11
It was 1 ppb or less, and no impurities other than silica were detected by emission spectroscopic analysis, and it was Shima Pure 1 (quality).

For comparison, 3. Fired product 1 was prepared using the same procedure as in Example 1 of Fi actual gun except that the nuclear No. 3 water glass was injected until the pH of the No. 3 water glass mixture reached 4.
I got 059-. The uranium content of this fired product is 52p
Due to the pH of PB and the production of hydrated silicic acid, the contamination of uranium increased by 4'4, which was found to be inappropriate and unsuitable.

, Patching cases 2, 3, 4, 5 Teflon coker (2, e pardon) to the OC table?
Add Sonoshizo fL 1.6, stir with a Teflon-coated inopeller-type rotating stirring rod, and pour in the water bath solution of Tani silica salt shown in the table.

(The pH of Kuntai liquid / J'' - 4 < 4 on the chart. Immediately after the water was raised, the injection of the water bath liquid was stopped, and the precipitate formed was of course the above-mentioned '-11-411i. The treatment was carried out in exactly the same manner as in Example 1 (1).
In particular, when Nitsu 1112 is used as the material, the uranium content will be less than 1 ppb, and the yield of quartz glass powder will be 9.
As in Example 1, all yields were high in the range of 2 to 96 hours.

Examples 6.7 and comparative examples.

+70 n beaker (213) lC2 regulation on +, t
1.2-e Money purse, 5I! For 1Ir11'5/pI6, this is followed by Sankei 1 wave magnesium (Mg no 813.06/5
H,o)? ! -170? , 13 in the corresponding comparative example
0y-, and in Example 7, IE calcium silane (Ca8i0
．． -'l, equivalent to 2H70) k2001/-, 160ft for the corresponding ratio bite example, and while stirring with a Teflon-coated impeller-type stirring device, JIllN degree 60°
After heating at C for 6 hours, the resulting precipitate was treated in the same manner as in Example 1 to obtain a dry silica gel powder.

Add this dry silica gel powder to: IA/Excretorrhea 1
It was found that the sodium and uranium content range in the stone residue glass powder was as shown in the table, and that these impurities were sufficient to obtain a fJ product.

Claims (3)

[Claims] (1) A reaction between an alkali metal or alkaline earth metal silicate and a mineral acid is carried out under conditions where the water ion concentration is 1.5 or less,
A method for preparing quartz glass powder, which comprises precipitating hydrated silica A2, washing, drying, and circulating the hydrated silicic acid precipitate. □ (2) The alkali metal silicate is water glass.Claims (1) A manufacturing method in the pressure range of 11 pi. (3) Claim that the mineral acid is nitric acid +1)
The manufacturing method described in.