JP3318893B2 - Metal contamination prevention high-speed stirrer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for atomizing particles by mixing a mixture of raw material particles and water at a high speed in order to obtain fine abrasive from raw material particles having a coarse abrasive. The present invention relates to a stirrer for preventing a metal component from being mixed into an abrasive during stirring or a stirrer for atomizing a substance which dislikes metal contamination. Abrasives that have been atomized by a stirrer that atomizes abrasives are used when a semiconductor disk such as a silicon wafer or other nonmetallic material is smoothly polished by chemical mechanical polishing (CMP) or the like. The raw material particles have, for example, an average diameter of about 5
The abrasive, which is 0 μm silica SiO ₂ or alumina Al ₂ O ₃ and is agitated at high speed into fine particles, has an average diameter of 0.1 to 0.2 μm.

[0002]

2. Description of the Related Art If a metal component is mixed in a polishing material for polishing a semiconductor, even if the amount is small, the polished semiconductor is contaminated with metal and its electrical characteristics are impaired. On the other hand, the stirrer and stirrer of the device used to atomize the raw material particles are easily worn by the polishing action of the raw material particles, and, for example, when a metal blade coated with a hard synthetic resin is used as the stirrer, Since the coat is worn away in a short time and the components of the metal blades are shaved and mixed into the raw material particles, it is necessary to frequently replace the stirrer. To prevent this, the stirrer and stirrer were made of non-metallic hard synthetic resin, and the stirrer was rotated at high speed in a mixture of raw material particles and water. Since the liquid temperature rises due to the frictional heat between the mixed liquid and the stirrer, the temperature of the stirrer also rises to lower the strength, and the stirrer is liable to breakage in the vicinity of the boss where the force is concentrated.

[0003]

SUMMARY OF THE INVENTION The present invention is intended to achieve both the application of high-density energy necessary for atomizing raw material particles and the prevention of metal wear which is inevitable to occur. Abrasion-resistant resin can be easily attached and detached as a liner for the stirring tank, and the heat resistance of the stirring tool is increased to prevent breakage of the stirring tool at high temperatures, and to produce fine particles free of metal contamination. It is an object of the present invention to obtain a stirrer having a reduced size.

[0004]

According to one aspect of the present invention, a drive shaft is arranged concentrically in a cylindrical stirring tank, and the inner diameter of the stirring tank is set to a predetermined value. Attach a slightly smaller diameter stirrer to the drive shaft, supply a small amount of liquid to be stirred into the stirring tank, rotate the stirrer at high speed with the drive shaft, and turn the liquid to be processed into a thin cylindrical shape along the inner surface of the stirring tank. In a high-speed stirring device for stirring while standing up, the stirring tank,
A metal outer tub having a cooling water chamber, an inner tub made of a hard synthetic resin having high wear resistance and electrical insulation and closely fitted to the inner surface of the outer tub, and an inner tub made of the same material as the inner tub. A stirrer provided with a ring-shaped dam plate provided at the upper end of the tank, the stirrer includes a stirrer integrally formed of a hard synthetic resin having high wear resistance, and a metal boss member detachably attached to a drive shaft, The stirring member 12 has a cylindrical portion having an outer diameter slightly smaller than that of the inner tank and provided through an infinite number of small holes in the radial direction, and an arm portion extending inward from the cylindrical portion. A boss portion made of a metal is fixed.

According to this means, since the portion of the stirring member of the stirrer and the inner tank are made of a hard synthetic resin, the metal is not exposed even if these portions are shaved with a material to be processed such as an abrasive. No components are mixed. In addition, since the boss of the stirrer is made of metal, the heat resistance of the boss increases, and the stirring can be continued even if the stirrer becomes considerably high temperature due to frictional heat of the stirrer. Can be made into fine particles in a short time.

[0006] Another means is as described in claim 2.
In claim 1, before the stirring tank of the high-speed stirrer,
A solid-liquid contactor comprising a stirring tank having a water supply port, a stirring tool driven by a drive shaft passing through the bottom of the stirring tank, and a hopper for raw material particles provided on the top of the stirring tank is provided. . According to this means, in the solid-liquid contactor, the raw material particles and the water are brought into solid-liquid contact quickly, and the processing by the high-speed stirrer is simplified.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a longitudinal section of a high-speed stirrer of the present invention, wherein 1 is a high-speed stirrer, 2 is its stirring tank, 3 is an outer tank made of metal, 4 is an inner tank made of hard synthetic resin, and 3 is an outer tank. The inner tank 4 has a bottomed cylindrical shape. The outside of the outer tub is covered with a water chamber cover 5 to form a cooling water chamber 5a, and an inflow pipe 6 and an outflow pipe 7 of the cooling water are connected. A drive shaft 8 is inserted into the center of the stirring tank 2 from above, and a stirring tool 9 is fixed by a sleeve 10 and a nut 11.

The stirrer 9 is a stirrer 1 made of a hard synthetic resin.
2 and a boss 13 made of metal, and both parts are bolts 14a.
And a nut 14b. The stirring member 12
Is shown in FIG. 2 and includes a cylindrical portion 12a and an arm portion 12b.
Consists of The cylindrical portion 12a is provided with an infinite number of small holes 15 in the radial direction, and the arm portion 12b is provided with six bolt holes 16 and eight communication holes 17. A bolt 14 for fixing the boss 13 is provided in the bolt hole 16.
a is inserted, and the mixture flows through the communication hole 17 at the time of stirring. A pipe 1 communicating with the inner tank 4 is provided at the bottom of the stirring tank 2.
8 and 19 are connected and used for supplying and discharging the mixed liquid.

An upper chamber 20, a seal case 21, and a bearing case 22 are hermetically fixed at an upper portion of the stirring tank 2, and an electric motor for driving the drive shaft 8 is disposed at an uppermost portion. A ring-shaped thick weir plate 23 made of a hard synthetic resin is sandwiched between the upper surface of the stirring tank 2 and the lower surface of the upper chamber 20, and a cooling water pipe is provided on the peripheral wall of the upper chamber 20 in parallel with the cooling water chamber 5a. A cooling water chamber 24 communicated with the cooling water chamber 24 and a mixed liquid outlet 25 are provided. A mechanical seal 26 having a sealing surface 26 a is provided in the seal case 21. The outlet 25 is opened to allow the product to flow out when the stirring operation is performed continuously, but closed when batch production is performed, and the product is supplied to the pipes 18 and 19.
Drain from one side.

As the hard synthetic resin used for the inner tank 4, the stirring member 12, and the weir plate 23, ultrahigh molecular weight polyethylene,
Hard versus abrasion nylon is suitable because of its abrasion resistance. The inner tank 4 needs to be tightly fitted to the inner surface of the outer tank 3 by interference fit in order to improve the heat transfer between the inner tank 4 and the inner surface of the outer tank 3, and high dimensional accuracy is required. The outer peripheral surface and the outer surface of the bottom wall of the formed inner tank 4 are desirably cut and finished, and the inner surface of the peripheral wall is desirably cut to maintain concentricity with the drive shaft 8. The thickness of the peripheral wall of the inner tank 4 is preferably as thin as possible so that heat conduction is good. When the inner diameter of the inner tank 4 is 80 mm, the thickness t is about 2 mm.

As for the stirring member 12, it is desirable that the inner and outer peripheral surfaces of the cylindrical portion 12a be cut and finished to accurate dimensions in order to maintain the balance of rotation. The material of the boss 13, the bolt 14a and the nut 14b is stainless steel or titanium.

In the apparatus shown in FIG. 1, a mixed solution of water and silica, ie, a silica slurry L, is supplied into the inner tank 4 of the stirring tank 2 to rotate the drive shaft 8, and the stirring tool 9 is rotated at a peripheral speed of 50 to 70 m / s.
When the slurry L is driven at a high speed, the slurry L is rotated by the stirrer 9, and is instantaneously brought into close contact with the inner surface of the inner tank 4 by centrifugal force to be stirred in the circumferential direction while forming a thin cylindrical shape. Then, it is also stirred by flowing from the upper and lower ends of the cylindrical portion 12a to the inside of the cylindrical portion and flowing radially from the small hole 15, and in a short time, the silica particles having an average diameter of 50 μm are 0.1 to 0.1 μm.
It can be crushed to particles of 0.2 μm or less.

The maximum amount of liquid stirred in the stirring tank 1 is the amount of liquid having a thickness T limited by the weir plate 23. If the amount of liquid exceeding this is supplied, the liquid flows out to the upper chamber 20. When the apparatus is operated continuously, the one having a predetermined particle size is the upper chamber 2
The supply amount is controlled so as to flow to 0, and in the case of batch operation, the liquid amount whose thickness becomes T or less is supplied. In any case, the metal parts of the drive shaft 8 and the boss 13 do not come into contact with the silica slurry L except for the moment of starting, so that they do not receive a polishing action from the silica, and the metal component does not mix with the slurry L. impossible.

FIG. 3 shows an atomizing apparatus including a step of bringing raw material particles and water into solid-liquid contact to form a liquid mixture, and a step of stirring this liquid mixture at high speed to highly disperse the liquid. In FIG. 3, reference numeral 1 denotes the high-speed stirrer shown in FIG. 1, and reference numeral 30 denotes a solid-liquid contactor used in the preceding step. The solid-liquid contactor 30 includes a stirring tank 31 and a stirring tool 32 having a drive shaft 33 inserted from the bottom.
And a charging hopper 34 provided above the stirring tank 31. It is desirable that the same hard synthetic resin as the inner tank 4 of the high-speed stirrer 1 be used for the inner surface of the stirring tank 31, and that the stirring tool 32 be made of the same material as the stirring tool 9.

A hopper 3 is provided above the input hopper 34.
6. A weighing hopper 35 having a powder feeder 37 and a load cell 38 is provided to supply a predetermined amount of raw material particles measured by the load cell 38 to the solid-liquid contactor 30. A liquid feed pump 39 for supplying water to the water supply port 39a is connected. Stirring tank 31
When the raw material particles are supplied from the powder feeder 37 while the stirring tool 32 is driven at a peripheral speed of 10 to 30 m / s,
Solid-liquid contact is made sufficiently.

The outflow pipe 45 of the solid-liquid contactor 30 is connected to the stirring tank 2
The outlet 25 of the high-speed stirrer 1 is connected to a cushion tank 48, and is taken out through a liquid feed pump 49 and a filter 50.

An example of use of the apparatus shown in FIG. 3 will be described with reference to data shown in FIG. Samples 1 to 3 described in FIG. 4 show an example in which silica and alumina having an average particle diameter of 46 μm are used as raw material particles and are processed while being taken out from the raw material bag 41.
In the solid-liquid contactor 30, the stirrer 32 is rotated at a peripheral speed of 28 m / s, each sample is stirred for 60 seconds, and then sent to the high-speed stirrer 1 to perform a stirring process.

Sample 1 is a mixed solution having a silica concentration of 17%, and the untreated metal ion concentration ppm is N
i 0.9, Cr 1.5, Fe 1.51, Na
It was measured as 1.6. After being stirred by the solid-liquid contactor 30, the respective concentrations are 0.91, 1.3, 1.2, <
It was measured as 0.01 ppm.
By stirring 5 times for 8 seconds each at a peripheral speed of m / s, the respective concentrations were 0.84, 0.94, 1.56, <0.
It was measured as 01 ppm.

In these numerical values, it is understood that the concentration after stirring is lower than that in the untreated state due to a measurement error, and it is considered that the metal ions do not increase or decrease during the stirring. The reason why the high-speed stirrer 1 intermittently stirs is to allow time for the mixed liquid whose temperature has been increased by frictional heat to be cooled from the cooling water chamber 5a side.

Sample 2 had a silica concentration of 10.5%.
, The untreated metal ion concentration is Ni
0.72, Cr 0.7, Fe 0.83, Na <
It was measured as 0.01 ppm. This was stirred by the solid-liquid contactor 30 and then by the high-speed stirrer 1 at a peripheral speed of 60 m / s for 7 seconds each.
The numerical values after the second stirring are slightly increased in Cr and Fe, but the measured values are increased and decreased, so it is within the range of measurement error, and it is considered that there is no increase or decrease in metal ions.

Sample 3 had an alumina concentration of 10.5.
%, The untreated metal ion concentration was not measured, but the concentration measured after treatment with a solid-liquid contactor, Ni
9.04, Cr 3.6, Fe 5.5, Na <
The numerical value of 0.01 ppm and the numerical value after stirring 22 times for 9 seconds each at a peripheral speed of 70 m / s with the high-speed stirrer 1 are as follows.
There is almost no change except for the increase to 22 ppm. It is considered that this Na was detected from those contained in the water.

As described above, according to the high-speed stirrer 1, the inner tank 4 in contact with the mixed liquid and the stirring member 12 of the stirrer 9 are used.
Is made of solid hard synthetic resin, so that metal ions do not enter into the atomized abrasive.

[0023]

As is apparent from the above description, according to the first aspect of the present invention, the use of a hard synthetic resin for the portion of the stirring member of the stirrer and the inner tank makes it possible to prevent contamination by metal components, The boss of the tool is made of metal, which increases the heat resistance and allows the stirring tool to continue stirring until the stirring tool becomes extremely hot due to the frictional heat of the stirring. Can be made into a fine abrasive or fine material in a short time. According to the second aspect of the present invention, there is an advantage that the solid-liquid contacting machine can quickly make solid-liquid contact between the raw material particles and water.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a high-speed stirrer according to the present invention.

FIG. 2 shows a stirring member, (a) is a plan view, (b) is a side view, and (c) is a cross-sectional view.

FIG. 3 is a flow chart of equipment using a high-speed stirrer and a solid-liquid contactor.

FIG. 4 is a table showing the metal ion concentration of an object to be treated.

[Explanation of symbols]

1 high-speed stirrer 2, 31 stirring tank 4
Inner tank 5a Cooling water chamber 8, 33 Drive shaft 1
2 Stirring member 12a Cylindrical part 12b Arm part
13 Boss 23 Weir plate 30 Solid-liquid contactor

Claims (2)

(57) [Claims] 1. A drive shaft is arranged concentrically in a cylindrical stirring tank, a stirrer having a diameter slightly smaller than the inner diameter of the stirring tank is attached to the drive shaft, and a small amount of the liquid to be treated is supplied to the stirring tank. In a high-speed stirrer that rotates the stirrer at a high speed with a drive shaft and stirs the liquid to be treated while rising in a thin cylindrical shape along the inner surface of the stirrer, the stirrer is a metal outer tank having a cooling water chamber. An inner tank made of a hard synthetic resin having high abrasion resistance and electrical insulation and closely fitted to the inner surface of the outer tank; and a ring-shaped weir plate provided at the upper end of the inner tank with the same material as the inner tank. The stirrer comprises a stirrer integrally formed of a hard synthetic resin having high wear resistance, and a metal boss member detachably attached to the drive shaft,
The stirring member 12 has a cylindrical portion having an outer diameter slightly smaller than the inner tank and penetrating through a myriad of small holes in the radial direction, and an arm portion extending inward from the cylindrical portion. A high-speed stirrer for preventing metal contamination, wherein a metal boss is fixed. 2. The stirring tank according to claim 1, wherein a stirring tank having a water supply port, a stirring tool driven by a drive shaft passing through the bottom of the stirring tank, and a stirring tank are provided in front of the stirring tank of the high-speed stirrer. A high-speed stirrer for preventing metal contamination, comprising a solid-liquid contactor provided with a hopper of raw material particles provided.