JP2003266309A - Lapping slurry liquid recycling device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automate a series of work of recovery, recycling and supply of lapping slurry liquid used in a lapping machine and to improve yield by fully decomposing aggregated grains of abrasive grains and by eliminating mixture of foreign substances so that the surface of a semiconductor wafer will not be scratched at lapping. <P>SOLUTION: The aggregated grains of the abrasive grains 40 are decomposed using oscillating sieve machines 6 and 15, and a liquid 31 for recycling including the abrasive grains 40 which have large specific gravity and can be recycled is left, while a waste liquid 32 including unnecessary rubbish with small specific gravity is eliminated. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method used in a lapping process among semiconductor wafer manufacturing processes, and more particularly, to recover a used lapping slurry liquid and regenerate it into a reusable lapping slurry liquid. Apparatus and method.

[0002]

2. Description of the Related Art In the lapping process of each process of manufacturing a semiconductor wafer, the semiconductor wafer is lapped by a lapping machine. At the time of lapping, a lapping slurry liquid containing abrasive grains is used. The abrasive grains are mainly composed of alumina or zirconium.

In the used lapping slurry liquid,
Semiconductor wafer carrier generated during lapping,
Since foreign substances such as semiconductor wafer waste (silicon Si) and surface plate waste (iron Fe) have entered, and the abrasive grains have aggregated as agglomerated grains, they cannot be reused as they are.

(1) Therefore, conventionally, after the lapping slurry liquid used in a semiconductor wafer manufacturing plant is dried to remove the lapping oil, the lapping oil is passed to another recycling plant, where iron and silicon are used. Lapping slurry liquid is prepared by dissolving the "waste" that is composed by removing it with hydrochloric acid etc. and taking out only reusable abrasive grains, transporting these reusable abrasive grains to a semiconductor wafer manufacturing plant and adding lapping oil. Is being implemented.

(2) Japanese Unexamined Patent Publication No. 2001-310260 discloses a slurry liquid used when cutting a work piece with a wire saw, and the used slurry liquid is used as an abrasive grain which can be used by using a decanter. The invention is described that separates into unnecessary "dust" such as chips.

(3) In Japanese Unexamined Patent Publication No. 2001-341074, a reusable abrasive grain is taken out by decomposing the agglomerated grains of the abrasive grain by using a vibrating sifter and drying or culturing the lapping slurry liquid. That invention is described.

[0007]

However, according to the above technique (1), a drying process and a transporting process are required to regenerate the lapping slurry liquid, which requires time and labor for the regenerating work and is not efficient. Absent. In addition, foreign substances other than abrasive grains may be mixed in during the transportation process. If the lapping slurry liquid is reused with foreign matter mixed in, scratches may be attached to the surface of the semiconductor wafer and the yield may be significantly reduced.

Therefore, there is a demand for development of a closed system capable of automatically performing a series of operations for collecting, regenerating and supplying used lapping slurry liquid in a lapping machine.

According to the above technique (2), it is possible to separate the usable abrasive grains and unnecessary "waste" depending on the difference in specific gravity. Cannot be disassembled. If the aggregated particles are reused without being decomposed and lapping is performed, the coarse abrasive grains cause scratches on the surface of the semiconductor wafer, resulting in a reduced yield.

According to the technique of (3) above, the agglomerated grains of the abrasive grains can be decomposed, but since it is only the technique of extracting the reusable abrasive grains by drying the lapping slurry liquid, the above (1) Similar to the technique (1), the problem that the drying process and the transporting process are required, the regeneration work is not performed efficiently, and the problem that foreign substances other than abrasive grains are mixed in the transporting process are still unsolved.

[0011]

[Means for Solving the Problems and Effects] The first invention is
In the lapping slurry regenerator that recycles the used lapping slurry liquid in the lapping machine and supplies it again to the lapping machine, the lapping slurry liquid used in the lapping machine is vibrated while the abrasive grains in the lapping slurry liquid are sieved. Over, the abrasive grains, the vibration sieving machine that regulates the particle size to the maximum particle size or less allowed by the lapping machine, the lapping slurry liquid that has been used in the lapping machine is introduced, and the waste liquid and the regenerating liquid having different specific gravities, respectively. And a separator for separating the lapping slurry liquid based on the regenerating liquid that has been sized to the maximum particle size or less by the vibrating screener and the waste liquid separated and removed by the separator. It is characterized in that it is supplied to the machine again.

A second aspect of the present invention is a lapping slurry liquid regenerating apparatus for regenerating the lapping slurry liquid used in a lapping machine and supplying the lapping slurry liquid again to the lapping machine, wherein the lapping slurry liquid used in the lapping machine is guided to the lapping slurry liquid. While vibrating the liquid, the abrasive grains in the lapping slurry liquid are sieved, and the abrasive grains are sized by a first vibrating sieving machine that regulates the abrasive grain to a first particle size or less, and the first vibrating sieving machine. The wrapping slurry liquid is introduced to separate the waste liquid and the regeneration liquid having different specific gravities, and the regeneration liquid from which the waste liquid has been separated and removed by the centrifuge is introduced to vibrate the regeneration liquid. , Sieving the abrasive grains in the liquid for regeneration,
A second vibrating and sieving machine that adjusts the grain size to a particle size smaller than the first grain size and smaller than or equal to the maximum grain size allowed by the lapping machine. It is characterized in that a lapping slurry liquid is prepared on the basis of a regenerating liquid whose particle size is equal to or smaller than the maximum particle size, and the lapping slurry liquid is supplied again to the lapping machine.

A third aspect of the present invention is a lapping slurry liquid regeneration method in which the lapping slurry liquid used in the lapping machine is regenerated and supplied to the lapping machine again, while vibrating the lapping slurry liquid used in the lapping machine, A first vibrating and sieving step in which the abrasive grains in the lapping slurry liquid are sieved to adjust the abrasive grains to a first particle size or less;
The lapping slurry liquid whose particle size is equal to or less than the particle size is separated into a waste liquid and a regenerating liquid having different specific gravities, and the regenerating liquid from which the waste liquid is separated and removed is vibrated,
A second vibrating and sieving step of sieving the abrasive grains in the reclaiming liquid and sizing the abrasive grains to a particle size smaller than the first particle size and not larger than the maximum particle size allowed by the lapping machine. And a lapping slurry liquid preparation step of preparing a lapping slurry liquid based on the liquid for regeneration that has been sized to the maximum particle size or less, and the prepared lapping slurry liquid is supplied to the lapping machine again. And

In a fourth aspect based on the third aspect, in the lapping slurry liquid preparing step, any one or any two or all of new wrap oil, new slurry liquid, and new abrasive grains are used. Is a step of additionally supplying to the regeneration liquid.

According to the present invention, the aggregating particles of the abrasive grains 40 are decomposed by using the vibrating screeners 6 and 15, and the centrifugal separator 10 is used to re-produce the particles having a higher specific gravity as compared with silicon "scraps". The reclaiming liquid 31 containing usable abrasive grains 40 is left, and the waste liquid 32 containing unnecessary "waste" having a low specific gravity is removed. Therefore, the aggregated particles of the abrasive grains 40 can be completely decomposed, and a series of operations of collecting, regenerating, and supplying the used lapping slurry liquid 30 in the lapping machines 61 to 6N can be automatically performed in a closed system. .

Therefore, the problems of the prior arts (1) and (3) are solved. That is, the regeneration work is efficiently performed.
Further, since the transportation process is not required, scratches are not formed on the surface of the semiconductor wafer due to the inclusion of foreign matter, and the yield is greatly improved.

Further, the problem of the prior art (2) is solved. That is, since the agglomerated particles can be completely decomposed, scratches are not formed on the surface of the semiconductor wafer due to the coarse abrasive particles, and the yield is greatly improved.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a lapping slurry liquid regenerating apparatus and a method thereof according to the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a lapping slurry liquid regeneration system of the embodiment. The lapping slurry liquid recycling system 1 shown in FIG. 1 is provided in a semiconductor wafer manufacturing factory and can automatically perform a series of operations of collecting, recycling and supplying used lapping slurry liquid in a lapping machine. It is a closed system.

As shown in FIG. 1, a plurality N of lapping machines 6 are provided.
1 to 6N are processing machines used in the lapping step of each step of semiconductor manufacturing, and perform the lapping processing while fixing the semiconductor wafer on the surface plate and supplying the lapping slurry liquid 30.

Here, the lapping slurry liquid 30 is composed of abrasive grains 40 containing alumina, zirconium or the like as a main component and having a uniform particle size distribution and a lap oil 50 mixed at a weight ratio of about 1: 4. It is an abrasive material.

Lapping slurry liquid 30 from the supply line 2
Are supplied to the lapping machines 61 to 6N. When the semiconductor wafer is fixed on the surface plate of the lapping machines 61 to 6N, the lapping slurry liquid 30 is supplied to the lapping machines 61 to 6N.
Is supplied to the lapping machines 61 to 6N when the semiconductor wafer is removed from the surface plate, the lapping oil 50
Only the plate is supplied and the platen is washed.

A separator (not shown) is provided between the lapping machines 61 to 6N and the recovery line 3, and the lapping slurry liquid 30 used in the lapping machines 61 to 6N is used.
Then, only the lapping slurry liquid 30 of the wrap oil 50 for cleaning is recovered in the recovery line 3.

The used lapping slurry liquid 30 recovered in the recovery line 3 is sent to the recovery tank 4 and temporarily stored in the recovery tank 4. The used lapping slurry liquid 30 stored in the recovery tank 4 is sent to the vibration sieving machine 6 by the pump 5.

The vibrating and sieving machine 6 uses the used lapping slurry liquid 30 to generate semiconductor wafer carriers (iron Fe) generated during lapping, scraps of semiconductor wafers (Si), scraps of surface plate ( Coarse particles such as iron (Fe) are removed and the agglomerated particles of the abrasive particles 40 are decomposed. The vibrating sieving machine 6 is different from the conventional sieving machine in that the sieving machine itself is vibrated and the particle size is adjusted.
Since the sieving machine is vibrating, it is possible to decompose agglomerated particles and prevent clogging of the mesh. The vibrating sieving machine 6 uses a mesh that regulates the grain size to 50 μm or less, and the grain size is adjusted to this grain size or less.
However, the mesh having a particle size of 50 μm or less is an example, and any mesh that can remove coarse dust may be used.

The lapping slurry liquid 30 sized by the vibrating screener 6 is sent to the magnetic filter 7. The magnetic filter 7 has a permanent magnet arranged in the flow path of the lapping slurry liquid 30, and the lapping slurry liquid 3 that passes through the flow path.
The iron content contained in 0 (the scrap of the platen of the lapping machines 61 to 6N and the scrap of the wafer carrier) is removed.

The lapping slurry liquid 30 that has passed through the magnetic filter 7 is sent to the tank 8 and is temporarily stored in the tank 8. The lapping slurry liquid 30 stored in the tank 8 is sent to the centrifugal separator 10 by the pump 9.

The centrifuge 10 centrifuges the lapping slurry liquid 30 from which iron has been removed into a regeneration liquid 31 and a waste liquid 32 having different specific gravities. That is, comparing the specific gravity of the abrasive grains 40 (alumina, zirconium) in the lapping slurry liquid 30 with the specific gravity of the scrap (silicon) of the semiconductor wafer, which is an unnecessary foreign substance,
(Alumina, zirconium) has a specific gravity of 4.1 g / cm3 and is heavy, and "waste" (silicon) has a specific gravity of 2.23 g / cm3.
It is light in degree. Therefore, the regenerating liquid 31 containing the abrasive grains 40
And the waste liquid 12 containing the scraps of the semiconductor wafer can be separated.

However, before being sent to the centrifuge 10, the weight ratio of the abrasive grains 40 to the wrap oil 50 becomes darker than the original ratio (1: 4). Therefore, the wrap oil 50 is supplied to the centrifugal separator 10 to adjust the weight ratio, and then the separation operation is performed.

The regenerating liquid 31 and the waste liquid 32 in the centrifugal separator 10
When the two are separated, one regenerating liquid 31 is sent to the recycle tank 11 and is temporarily stored in this recycle tank 11, and the other waste liquid 32 is sent to the waste liquid tank 12 and is once stored in this waste liquid tank 12. It

The waste liquid 32 stored in the waste liquid tank 12 is sent to the waste liquid tank 16 by the pump 14. The waste liquid 32 stored in the waste liquid tank 16 is sent via a pump 17 to a waste liquid processing device (not shown) for waste liquid treatment.

The regenerating liquid 31 stored in the recycle tank 11 is sent to the vibrating and sieving machine 15 by the pump 13.

The vibrating and sieving machine 15 decomposes the agglomerates of the abrasive grains 40 in the regenerating liquid 31 and allows the maximum grain size of the abrasive grains 40 to be reused by the lapping machines 61 to 6N. The particle size is adjusted to be equal to or less than the diameter. The vibrating sieving machine 15 adjusts the particle size while vibrating the sieving machine itself like the vibrating sieving machine 6. Since the sieving machine is vibrating, it is possible to decompose agglomerated particles and prevent clogging of the mesh. The vibrating sieving machine 15 uses a mesh that regulates the grain size to 25 μm or less, and the grain size is adjusted to this grain size or less. This particle size 25
[mu] m is the maximum grain size of the abrasive grains 40 allowed for reuse in the lapping machines 61 to 6N, and is determined by the depth to which the surface of the semiconductor wafer is polished. However, the mesh having a particle size of 25 μm or less is an example, and is determined according to the degree of polishing.

Regeneration liquid 3 sized by vibrating sieving machine 15
1 is sent to the compounding tank 17.

A new lapping oil 50, a new slurry liquid 30, and a new abrasive grain 40 are additionally supplied to the regenerating liquid 31 sent to the mixing tank 17. As a result, the abrasive grains 40 and the wrap oil 50 are finely adjusted to the original weight ratio (1: 4). That is, rough adjustment is performed by supplying new wrap oil 50 to the centrifuge 10, but fine adjustment is performed in this mixing tank 17.

In the mixing tank 17, a new lapping oil 50, a new lapping slurry 30 and a new abrasive grain 40 are additionally supplied, but the ratio of the abrasive grain 40 to the lapping oil 50 is adjusted to a desired ratio. Any one or any two of them may be additionally supplied to the regeneration liquid 31 as long as it can be adjusted.

The regenerating liquid 31 whose weight ratio is finely adjusted in the mixing tank 17 is the reusable lapping slurry liquid 30.
Is sent to the supply line 2 by the pump 18.

As described above, according to this embodiment,
The vibrating sieving machines 6 and 15 are used to decompose the agglomerates of the abrasive grains 40, and the centrifuge 10 is used to leave the regenerating liquid 31 containing the reusable abrasive grains 40 having a large specific gravity, and thus the specific gravity is unnecessary. The waste liquid 32 containing a large amount of "waste" is removed. Therefore, the agglomerated particles of the abrasive particles 40 can be completely decomposed, and the lapping slurry liquid 30 that has been used by the lapping machines 61 to 6N can be completely decomposed.
It is possible to automatically perform a series of operations of recovery, regeneration, and supply of the oil in a closed system.

Therefore, the problems of the prior arts (1) and (3) are solved. That is, the regeneration work is efficiently performed.
Further, since the transportation process is not required, scratches are not formed on the surface of the semiconductor wafer due to the inclusion of foreign matter, and the yield is greatly improved.

Further, the problem of the prior art (2) is solved. That is, since the agglomerated particles can be completely decomposed, scratches are not formed on the surface of the semiconductor wafer due to the coarse abrasive particles, and the yield is greatly improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a lapping slurry liquid regeneration system of the present embodiment.

[Explanation of symbols]

1 Wrapping slurry liquid regeneration system 6,15 Vibrating sieving machine 10 Centrifuge 61-6N Lapping Machine

Claims (4)

[Claims] 1. A lapping slurry liquid regenerator that regenerates the lapping slurry liquid used in a lapping machine and supplies it again to the lapping machine, wherein the lapping slurry liquid used in the lapping machine is vibrated while in the lapping slurry liquid. Sieving the abrasive grains of
A vibrating and sieving machine that regulates the abrasive grains to the maximum particle size allowed by the lapping machine and a lapping slurry liquid that has been used in the lapping machine are introduced, and separated into waste liquid and regeneration liquid that have different specific gravities. With a separator to, based on the regenerating liquid that has been sized to less than or equal to the maximum particle size in the vibrating screener, and waste liquid separated and removed in the separator,
A lapping slurry liquid regenerator characterized in that a lapping slurry liquid is prepared and supplied again to the lapping machine. 2. A lapping slurry liquid regeneration device for regenerating the lapping slurry liquid used in a lapping machine and supplying it again to the lapping machine, wherein the lapping slurry liquid used in the lapping machine is guided to vibrate the lapping slurry liquid. While sieving, the abrasive grains in the lapping slurry liquid are sieved, and the first vibrating and sieving machine that regulates the abrasive grains to a first particle size or less, and the lapping slurry sized by the first vibrating and sieving machine. A separator that guides the liquid and separates it into a waste liquid and a regeneration liquid that have different specific gravities, and a regeneration liquid from which the waste liquid has been separated and removed by the centrifuge is introduced, and while vibrating the regeneration liquid, the regeneration liquid is recycled. A second vibrating sieving machine for sieving the abrasive grains in the liquid and sizing the abrasive grains to a grain size smaller than the first grain size and smaller than or equal to the maximum grain size allowed by the lapping machine. Comprises the second Based on the abrasive grain liquid for reproduction is granulated under maximum particle diameter or less by the dynamic sifter, lapping slurry solution regeneration system formulated lapping slurry liquid, characterized in that re-supplied to the lap machine. 3. A method of regenerating a lapping slurry used in a lapping machine and re-supplying the lapping slurry to a lapping machine, wherein the lapping slurry used in the lapping machine is vibrated while being vibrated. The specific gravity of the first vibrating and sieving step of sieving the abrasive grains therein to regulate the abrasive grains to a first grain size or less and the lapping slurry liquid sized to the first grain size or less Separation step of separating into different waste liquid and regenerating liquid, and vibrating the regenerating liquid from which the waste liquid has been separated and removed, and sieving the abrasive grains in the regenerating liquid to sieve the abrasive grains to the first particle size. A second vibrating and sieving step in which the particle size is smaller than the maximum particle size allowed by the lapping machine, and a lapping slurry liquid based on the regenerating liquid that has been particle size adjusted to the maximum particle size or less. Lac to mix And a Ngusurari liquid preparation step, a lapping slurry solution regeneration method and supplying again the wrapping slurry liquid which is formulated in the lap machine. 4. The lapping slurry liquid preparation step additionally supplies any one or any two or all of a new wrap oil, a new slurry liquid, and new abrasive grains to a regeneration liquid. The lapping slurry liquid regeneration method according to claim 3, which is a step of