KR101525543B1 - Method for recycling waste-abrasive used in the lapping and polishing of semiconductor and industry wafer - Google Patents

Abstract

The present invention relates to a method of collecting a whole quantity of waste abrasive generated from cutting and polishing processes of a semiconductor wafer and industrial wafer, including a lapping process of a sapphire wafer, and the like, and of recycling the same. The method comprises the processes of: first and second adjusting a percentage of water content of waste abrasive containing boron carbide (B_4C) which is included in expensive, rare minerals as abrasive components; first cleaning and stirring using a chemical reaction; second cleaning and stirring using Di warm water; drying; crushing; and sorting. Accordingly, recycled abrasive containing boron carbide (B_4C), which is a coarse powder, is obtained such that the boron carbide (B_4C) of waste abrasive, which is a rare mineral, is recycled with high purity. Also, the boron carbide (B_4C) is divided and sorted into a coarse powder and a fine powder, whereby each waste abrasive containing the boron carbide (B_4C) can be recycled as a raw material of abrasive with high purity and refractory.

Description

Technical Field [0001] The present invention relates to a method of recycling a waste abrasive used for cutting and polishing wafers in semiconductors and industrial wafers,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to regeneration of abrasives, and more particularly, to recycling waste abrasives generated in a cutting and polishing process of semiconductor and industrial wafers including a sapphire wafer lapping process, thereby reducing waste of resources and environmental pollution The present invention relates to an improvement of a reproducing method which can be prevented in advance.

Boron carbide (B ₄ C, Boron Carbide), a kind of rare minerals, has a Mohs hardness of about 9.5 and its strength is hard and strong artificial minerals that are intermediate between diamond and silicon carbide. It is widely used as processing main ingredient.

Currently, companies producing or intermediate processing LED displays are required to perform a lapping process, which is a wet grinding process, for semiconductor and industrial wafers such as sapphire wafers for LEDs. In this lapping process, boron carbide (B ₄ C), which is a rare rare minerals, is used for improving smoothness and maintaining gloss.

Therefore, a company that uses boron carbide as an abrasive will import almost all of its products from abroad and use it in industrial wafer cutting and polishing processes. As the abrasive and cutting efficiency of boron carbide abrasive decreases, it can not be used. It is classified as general wastes and the whole is buried at a high cost.

In order to solve the present problems caused by environmental pollution and waste of resources, it is necessary to recycle waste abrasives more efficiently and to prevent environmental pollution caused by recycling of resources and reclamation of recycled abrasives, You will get a response.

The prior art mentioned below in the prior art is based on the inventors of the present invention as an abrasive regeneration method, in which ultrasonic waves are used for cleaning the abrasive abrasive, which is not efficient, has a cleaning limit, There is a disadvantage in that a large amount of equipment is provided.

Japanese Patent Application Laid-Open No. 10-1381728 entitled "Method for regenerating abrasive in sapphire wafer lapping process"

Accordingly, an object of the present invention is to provide a method of recycling a waste abrasive material, which enables a boron carbide (B ₄ C) component, which is a rare mineral, to be recycled at a high purity as an abrasive component contained in a waste abrasive material produced by a company producing semiconductor or industrial wafers have.

According to the present invention, there is provided a method for regenerating a waste abrasive material, which comprises a sapphire wafer and is produced in a process of cutting or polishing a semiconductor or an industrial wafer, comprising the steps of drying a waste abrasive material in a suspension state, To 35% by weight, a second moisture content controlling step of rehydrating a waste abrasive material having a first moisture content adjusted to 30 to 35% by weight to obtain a moisture content of 15 to 20% by weight, A waste abrasive having a moisture content of 20% by weight and Di (De-ionized) hot water at a weight ratio of 1: 1 to 1: 2 are introduced into a cleaning vessel and the chemical reaction settling inducing agent is added in an amount of 0.05 to 0.5% by vortex stirring particles in the aggregated state are to be separated by a chemical reaction and the specific gravity difference with the abrasive component is boron carbide (B ₄ C) 1 car washing under stirring to precipitate the component and separating the supernatant waste liquid finely divided are contained and remove the And, many times, but the primary cleaning stirring boron carbide obtained by the process (B ₄ C), insert the needle cheonmul in the cleaning container by using a Di water sikimyeo precipitated after stirring washed to remove the supernatant containing the remaining fine powder and oil, and removing (B ₄ C) component obtained in the second washing and stirring step is dried to have a water content of less than 0.3 wt% by thermally drying the precipitate of the boron carbide (B ₄ C) component, (B ₄ C) component after the drying process, and a crushing process for crushing the dried product after the drying process, and one of boron carbide boron (B ₄ C ) Component and a boron carbide (B ₄ C) component for an abrasive, which is a fine powder, are selected.

In the waste abrasive recycling method of the present invention, the first and second moisture content control processes and drying processes are performed using at least one of mechanical dehydration, natural drying using a surrounding environment, and forced drying using a heat source.

In the primary cleaning agitation process, the agitation is carried out using a heater mounted inside the cleaning vessel while heating at 30 ° C to 35 ° C, and agitation by vortex can be performed using a vortex formation induction plate installed in the square cleaning vessel .

Further, in the present invention, a horizontal type decanter is used in parallel to accelerate the difference in specific gravity between the crude powder as the abrasive ingredient in the cleaning vessel and the washing waste liquid containing the fine powder as the impurities in the primary washing agitation step. do.

In the present invention, in the fining operation of the sorting process, a micro sieve is used to perform a repeated firing operation from one time to several times in accordance with a desired grain size to remove boron carbide (B ₄ C) components for abrasive and non- It is characterized in that a mesh screen having various sizes of eyes is installed in multiple layers, or a mesh screen having the same size of eyes is installed in a single layer or multiple layers so as to carry out atomization.

The present invention relates to a method of collecting all the abrasive abrasives generated from a semiconductor or industrial wafer producing company and controlling the primary and secondary moisture content, primary washing agitation using a chemical reaction, secondary washing agitation using Di hot water, drying, (B ₄ C), which is a rare mineral contained in abrasive waste, is recycled as a raw material for high purity abrasives and refractories by regenerating high purity components and separating them into fine powders or fine powders.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process flow chart for regenerating a waste abrasive containing boron carbide (B ₄ C), a rare mineral, according to an embodiment of the present invention;
FIGS. 2A and 2B are schematic views of a cleaning container in a primary cleaning agitation process. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the production of LED displays and the like, processing of semiconductor and industrial wafers such as a sapphire wafer lapping process, that is, wet polishing of wafers for semiconductors and industrial wafers for improving the smoothness of the wafers and maintaining the luster is carried out, Is generated. These abrasive abrasives are in the form of a slurry. These abrasive abrasives contain not only boron carbide (B ₄ C) coarse components, which are expensive rare minerals contained in the abrasive for wafer processing but also alumina (Al ₂ O ₃ ) ₂ O ₃ ) or iron (Fe), and a silicon (Si) component, as well as a water-soluble liquid dispersant and chemical additives.

In the present invention, effective substances such as boron carbide (B ₄ C), which are expensive rare minerals, are separated from the abrasive abrasive generated in the course of polishing, respectively, and can be separated into high purity at 90 wt% or more.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process flow chart for regenerating a waste abrasive containing boron carbide (B ₄ C), which is a rare mineral, according to an embodiment of the present invention. The process includes a first water content control process (S100), a second water content control process (S102) The first cleaning agitation step S104, the second cleaning agitation step S106, the drying step S108, the shattering step S110, and the selection step S112.

The boron carbide (B ₄ C) component, which is an expensive rare mineral among the particles agglomerated in the suspension of abrasive abrasive material which has lost the abrasion rate, mainly corresponds to the coarse particles having a particle size of 5 to 100 μm as the main component of the abrasive, Al ₂ O ₃ , ferric oxide (Fe ₂ O ₃ ), iron (Fe), and silicon (Si) components correspond to derivatives having a particle size of less than 5 μm.

It is preferable that such a waste abrasive material is transferred to an airtight container for regeneration and transferred to a waste abrasive recycling facility according to the present invention, and is supplied to a regeneration facility to perform a regeneration procedure according to an embodiment of the present invention.

First, in the present invention, a moisture abrasive containing boron carbide (B ₄ C) components, impurities, and the like is sequentially subjected to a first and a second water content adjustment process as in steps S100 and S102 of FIG.

In the process of controlling the primary moisture content (S100), a mechanical dewatering method such as a centrifugal separation method or a filter press method is selectively applied to a suspended abrasive material in a suspension state, and a natural drying method using a surrounding environment such as natural evaporation, So that the water content is 30 to 35% by weight. Preferably, a mechanical dewatering method such as a centrifugal separation method or a filter press is preferable, and the water content is measured by a moisture meter.

Then, in the second moisture content regulation process (S102), the waste abrasive having a primary moisture content adjusted to 30 to 35% by weight is dried again by a forced drying method using a heat source or air blowing to have a water content of 15 to 20% by weight.

When the water content of the abrasive material is 15 to 20% by weight through the first and second water content control processes (S100 to S102), the separation efficiency is maximized when the chemical reaction is induced in the first washing agitation step (S104) The present inventors have confirmed this. This is because the water-soluble liquid dispersant or the chemical additive contained in the liquid component in the suspension interferes with the chemical reaction in the primary washing and stirring step (S104), so that the water content is appropriately removed through controlling the water content.

In the present invention, a primary washing agitation step (S104) is performed after the waste abrasive has a water content of 15 to 20 wt% by controlling the secondary moisture content by the drying treatment. In the primary washing agitation step (S104) .

In the primary cleaning agitation step (S104), a waste abrasive having a water content of 15 to 20 wt% and Di (De-ionized) hot water (30 to 35 DEG C) are mixed at a weight ratio of 1: Is mixed in the cleaning container 10 and the chemical reaction settling inducing agent is added in an amount of 0.05 to 0.5% by weight (preferably 0.1% by weight) of the total mixture volume, The agitator 12 is agitated to cause the particles in the agglomerated state to separate and precipitate by a chemical reaction. As the chemical reaction settling inducer, a polymer-based chemical reaction settling inducer containing a surfactant is used.

The rectangular cleaning vessel 10 is a dedicated cleaning vessel equipped with a heater inside the vessel, and the stirring is progressed at a temperature of 30 ° C to 35 ° C by using the heater. In addition, in the present invention, as shown in FIG. 2A, a vortex formation induction plate 14 for forming a vortex in the fluid flow by the rotation of the agitator 12 is provided on the wall of the rectangular cleaning vessel 10, So that stirring can be performed. That is, a plurality of vortex formation induction plates 14 made of a rectangular plate at an angle of 90 degrees in the rotating direction of the agitator 12 are mounted on the container wall body.

The vortex action during agitation of the mixture by the agitator 12 aids in the rapid settling of the chemical reaction and coarse fraction (boron carbide (B ₄ C) component).

In the primary cleaning agitation step (S104), the mixture and agglomerated coarse and fine particles are separated through agitation, and after agitation, they are left for 1 to 3 hours, And the specific gravity difference.

It should be understood that, in the present invention, an artificial operation using a horizontal type decanter may also be performed in parallel to accelerate the difference in specific gravity between the raw powder as the abrasive ingredient and the washing waste containing the fine powder treated as the impurity.

2B, the particles of the rectangular cleaning container 10 are rapidly precipitated as a coarse abrasive component, that is, a boron carbide (B ₄ C) component, by the particle size and the specific gravity difference, (16a) to form an alumina (Al ₂ O ₃₎ and iron sesquioxide (Fe ₂ O _3), iron derivative, many of less than 5㎛ such as (Fe), silicon (Si) component is contained in the supernatant the waste (16b) .

(B ₄ C) component sediments 16a (16a), which are rare minerals mainly composed of coarse fractions, are formed in the rectangular cleaning vessel 10 by sucking up the recycle waste liquid 16b by suction pump ).

After the first washing and stirring step (S104) in FIG. 1, the present invention performs a second washing and stirring step (S106) using Di (De-ionized) hot water (30 to 35 ° C).

In the secondary washing and stirring process (S106), the precipitate (16a) having been subjected to particle separation is mixed with DI hot water in a washing container at a weight ratio of 1: 1 to 1: 2, stirred with a stirrer, So that a natural precipitation of the boron carbide (B ₄ C) component is achieved. After the natural precipitation, the supernatant containing foreign matter such as residual fine particles or small amount of oil is sucked out by suction pump or the like.

(4 to 5 times) in which the boron carbide (B ₄ C) component, which is an abrasive component, is precipitated by washing with DI water, and then proceeds to the next step.

The final recovery rate of the secondary cleaning agitation step (S106) of the present invention is 45 to 60% of the initial amount of the sediment 16a, which has been subjected to the chemical reaction through the primary washing agitation step (S104) It means when it becomes. The inventors of the present invention have confirmed through experiments that the amount of the boron carbide (B ₄ C) component contained in the sediment after the second washing and stirring step (S106) is more than 90 wt%.

After the second washing and stirring step (S106), water is removed until the water content of the precipitate becomes a predetermined amount (preferably 30% by weight) by the forced removal method or the natural evaporation method, and the water content reaches the target value The process proceeds to the next step.

After the secondary cleaning agitation step (S106) is completed, the drying step (S108) is performed.

Drying process (S108) in the sikidoe put into the precipitate of boron carbide (B ₄ C) completed the secondary cleaning stirring process (S106) in the dryer when the temperature is 250 ~ 300 ℃ of the dryer components heat drying the moisture remaining in the precipitate , And dried until the water content becomes less than 0.3% by weight to obtain a washed and dried boron carbide (B ₄ C) component.

After the drying process (S108) is completed, the crushing process (S110) is performed, which is a pretreatment process for maximizing the efficiency of micro sieve performed in the selection process (S112).

In the crushing process (S110), the crushed and dried boron carbide (B ₄ C) component is crushed by a crusher to crush the crushed boron carbide (B ₄ C) component into fine particles of boron carbide (B ₄ C) .

The boron carbide (B ₄ C) washed and dried product after the disintegration process (S 110) is subjected to a screening process (S 112) to be performed in a subsequent step S112 wherein the content of the boron carbide (B ₄ C) component is 90 wt% To obtain a reclaimed abrasive having the following coarse powder.

That is, in the selection process (S112), the washed and dried material that has been subjected to the crushing process (S110) is subjected to a firing operation using a micro sieve, and is repeatedly fired for one to several times in accordance with the desired particle size, The boron carbide (B ₄ C) component (coarse fraction) is selected. The fine powders obtained from the fission work can be used as recycled refractories by separately classifying them as boron carbide (B ₄ C) components for non-abrasive materials.

The structure of the microresistant branch is preferably a plurality of mesh screens having various sizes of eyes, or a mesh screen having the same size of eyes, in a single layer or multiple layers, In order to uniformize the particle size of the washed and dried material by a fountain operation from one time to several times.

Through this sorting step (S112), the boron carbide (B ₄ C) component (coarse powder) reclaimed abrasive with the fine particles removed is of the same quality level as the new abrasive.

Among the screening methods of the present invention, there is a disadvantage in that a fibrillation work process using a micro sieve requires a plurality of fibrillation steps in order to reach a desired quality level (quality equivalent to a new abrasive) As another method, it is to be understood that a crude boron carbide (B ₄ C) component reclaimed abrasive obtained by removing boron carbide (B ₄ C) fine particles in a short period of time can be obtained by an air stream type classification operation using an air stream type classification apparatus.

As described above, the present invention can recycle boron carbide (B ₄ C), a rare minerals contained in a waste abrasive, and recycle it as an abrasive such as a sapphire wafer or the like. Boron carbide (B ₄ C) reclaimed abrasives can be used in the form of liquid slurries and dry powders. In addition, recycled boron carbide (B ₄ C) with fine grain size that can not be used as a reclaimed abrasive can be used as a refractory material (both regular and amorphous).

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. Therefore, the scope of the present invention should not be limited by the described embodiments, but should be determined by the scope of claims and equivalents thereof.

The product obtained by the present invention can be used as a reclaimed abrasive (liquid-slurry form and dry-powder form) or refractory materials (both regular and amorphous) And may be used as a deoxidizing agent raw material which is consumed in a large amount in industry.

(2) - square cleaning container
(12) - Agitator
(14) - vortex formation induction plate

Claims (5)

1. A method of recycling a waste abrasive material comprising a sapphire wafer and occurring during a process of cutting or polishing a semiconductor or industrial wafer,
A primary moisture content controlling step of drying a waste abrasive material in a suspension state so that a moisture content of the waste abrasive material is 30 to 35% by weight,
A second moisture content controlling step of rehydrating a waste abrasive material whose primary moisture content is controlled to 30 to 35% by weight to obtain a water content of 15 to 20% by weight,
(1) to (1: 2) by weight of a waste abrasive having a moisture content of 15 to 20% by weight and Di (de-ionized) hot water in a cleaning vessel, wherein the chemical reaction settling inducer is contained in an amount of 0.05 to 0.5% (B ₄ C) is precipitated by using the difference in specific gravity, the particles in the coagulated state are separated by the vortex agitation after the addition, and the primary phase containing the fine powder is removed and removed. Washing and stirring process,
First, the boron carbide (B ₄ C) precipitate obtained from the first washing and stirring process was put in a washing container, and the mixture was precipitated by stirring with DI water, and the supernatant containing residual fine powder and oil was separated and removed. A second washing and stirring step of repeating the steps of
Drying the precipitate of the boron carbide (B ₄ C) component obtained in the second rinsing stirring step to obtain a dried boron carbide (B ₄ C) component by drying it to have a water content of less than 0.3 wt%
A crushing process for crushing the dried and cleaned boron carbide (B ₄ C) component after the drying process,
Characterized in that after crushing constituted by any sorting process for sorting the chebun operation or air current type of boron carbide for abrasive one trillion minutes using one thing the classifier working (B ₄ C) an abrasive boron carbide for the component and the derivative (B ₄ C) component Waste abrasive recycling method used in semiconductor and industrial wafer cutting and polishing.
[2] The method of claim 1, wherein the first and second moisture content regulation processes and drying processes are performed using at least one of a mechanical dehydration process, a natural drying process using a surrounding environment, and a forced drying process using a heat source. A method of recycling a waste abrasive used in cutting and polishing.
2. The method according to claim 1, wherein in the first cleaning agitation step, the agitation is carried out using a heater installed inside the cleaning vessel while heating at 30 to 35 DEG C, Wherein the abrasive material is used in cutting and polishing wafers for semiconductor and industrial wafers.
4. The method according to claim 1 or 3, wherein a horizontal decanter is used in parallel to accelerate the difference in specific gravity between the washing powder containing the abrasive ingredient in the washing container and the washing waste containing the fine powder in the first washing agitation step Wherein the abrasive material is used for cutting and polishing wafers for semiconductor and industrial purposes.
The method of claim 1 or 3, wherein the fractionating operation of the sorting process is performed by repeating a sieving operation from one to several times in accordance with a desired particle size using a micro sieve to remove boron carbide for abrasive and non- B ₄ C) Select the components, install multiple mesh screens with various sizes of eyes, or install mesh screens (Mesh Screen) with the same size of eyes in one layer or multiple layers, Wherein the abrasive material is used in cutting and polishing wafers for semiconductor and industrial wafers.

Images