KR101385947B1 - Depth filter for filtering cmp slurry - Google Patents

Abstract

The present invention relates to a depth filter for slurry filtration of the CMP process.
The depth filter of the present invention is composed of a multi-layered media layer having a porosity gradient to gradually increase the average pore size from the inner core to the outer circumferential surface, and maintains the same average pore size of the media forming the media layer to provide an asymmetric pore gradient. While maintaining, by providing a depth filter finely finely average fiber fineness, the porosity in the depth filter media is increased, excellent fine particle removal ability, excellent particle trapping ability of a certain size, increase the use cycle. Furthermore, the depth filter of the present invention is useful as a depth filter for slurry filtration in a CMP process.

Description

Depth filter for slurry filtration of CPM process {DEPTH FILTER FOR FILTERING CMP SLURRY}

The present invention relates to a depth filter for slurry filtration of the CMP process, and more particularly, to maintain asymmetric pore gradients while maintaining the same average pore size of the media forming the media layer, The present invention relates to a depth filter for slurry filtration of a CMP process, by increasing the number of porosity and pore size in the depth filter medium, having excellent ability to remove fine particles and particles of a certain size, and increase the use cycle.

Wafer polishing technology using a chemical mechanical planarization (CMP) slurry has advantages such as high polishing efficiency and ease of operation compared to conventional etching methods, and replaces conventional conventional etching processes.

However, a wafer polishing technique using a CMP slurry has a problem in that scratches are generated by large particles in the slurry during polishing. In order to solve this problem, a filter for filtering a CMP slurry in slurry production is used.

However, even if the slurry is sufficiently filtered, there is a high possibility that agglomerates are formed at the time of storage, transportation, and dilution depending on pH, temperature, and the like.

Therefore, various types of filters are applied to the actual CMP process. In particular, a number of studies have been reported that slurry filtration using a filter during the CMP process reduces wafer scratches, thereby increasing the yield of the overall process.

The filter used in the CMP process is designed so that larger particles of a certain size or more are selectively collected and removed in the filter structure, and small particles of a certain size or less pass through the filter after filtration for wafer polishing. Therefore, the CMP filter has the characteristics of particle separation rather than particle removal, and therefore, an absolute grade level of particle exclusion performance is required.

Generally, the process filter for filtration is classified into a deep filter in the form of a cartridge and a membrane filter in the form of a membrane.

Membrane filters are typically manufactured in the form of cartridges by bending thin membranes of several tens of microns and have a high level of flow characteristics due to the maximum surface area. In the membrane filter, particles are removed by pores formed on the surface of the thin polymer membrane, and all particles larger than the pore size are removed.

However, CMP slurries have a very high solids content compared to the process solution, and when a filter in the form of a membrane is applied, pore closure by solid particles occurs immediately after filtration, which is not suitable.

Therefore, in order to filter CMP slurry, it is generally preferable to use a filter having a deep structure.

The depth filter is not a surface filtration but a slurry filtration mechanism that removes particles by trapping particles inside the filter while passing through a nonlinear tortuosity in a media layer having a thickness of several mm to several tens of mm.

However, due to the characteristics of the removal mechanism, the depth of particle removal is not sharper than that of the membrane filter when the depth filter is used, and there is another problem that a small amount of large particles may exist even after filtration.

Therefore, in order to solve this problem, the core technology of maximizing the removal performance and extending the service life as much as possible by optimizing the type and structural design of the fiber media constituting the filter when manufacturing the depth filter for slurry filtration in the CMP process To be.

Thus, a deep filter for removing particles is generally produced by winding a nonwoven fabric in a cylindrical shape on a core or by manufacturing a filter in a cylindrical shape on a surface of a core by direct spinning of a polymer.

Particle removal by such a depth filter is designed to collect the particles in the deep structure of the non-woven fabric that is directly spun or rolled, in which a plurality of individual layers having different average pore sizes are composed so that particles of each size are separated and collected. That is, as the fluid is introduced into the housing, large particles in the fluid are preferentially collected and removed from the outermost portion of the cylindrical filter having a relatively large pore size, and then the fluid flows inward, becoming more and more closer to the core. Relatively small particles are collected and removed by the media layer having a small pore size, so that the flow rate and the removal efficiency are maximized.

Typically, in the design of such an asymmetric filter, a gradient is given at the average pore size level of the media layer used to optimize the particle removal ability and the differential pressure level for each filter grade, so that each layer selectively collects particles of a certain size range.

However, in order to improve the useful life of the filter and the particle trapping ability of a certain size range, increasing or decreasing the composition ratio of a specific layer may break the degree of asymmetry on the pore size and affect the removal performance and the differential pressure level.

Therefore, in order to maintain the degree of asymmetry of the pore level and the differential pressure level, and to improve particle trapping ability, the porosity of each layer in the depth filter should be increased, and for this purpose, the number of pore sizes should be increased while providing the same average pore size.

Accordingly, the present inventors have tried to solve the problems of the prior art, by maintaining the same average pore size of the media constituting the media layer to maintain the asymmetric pore gradient, by controlling the average fiber fineness, to increase the porosity in the deep media By providing the same average pore size, increasing the number of pore size, excellent in the ability to remove microparticles, improved particle trapping ability of a certain size, by producing a deep filter with increased use cycle, the present invention was completed.

An object of the present invention is to provide a depth filter for slurry filtration of the CMP process.

Another object of the present invention is a depth filter made of a multilayer filter layer in which an asymmetric pore gradient is given so that the average pore size gradually increases from the inner core to the outer circumferential surface, by controlling the fineness of the average fiber of the filter medium, It is to provide a depth filter for slurry filtration of the CMP process with excellent particle trapping ability of a certain size.

In order to achieve the above object, the present invention is a depth filter composed of a multi-layer filter layer which is provided with an asymmetric pore gradient such that the average pore size gradually increases from the inner core to the outer peripheral surface, the same average pore size of the media constituting the filter layer To provide a depth filter for slurry filtration of the CMP process, while maintaining the average fiber fineness is provided with a fine-grained depth filter to increase the number of porosity and pore size in the depth filter.

In the depth filter for slurry filtration of the CMP process of the present invention, the fineness of the average fiber is 80% or less with respect to the average fiber fineness of 1 to 40㎛ in the average pore size of the filter medium, wherein the finely divided deep filter media It is refined to.

At this time, the average pore size of the media is 1 to 30㎛.

The multi-layered media layer is composed of at least three to six layers, characterized in that the at least one median layer is a finely divided deep media.

The media constituting the media layer of the present invention is any one material selected from the group consisting of polyethylene, polypropylene, polyester, polyolefin and polyamide, and includes spunbond, heat bond, spunlace, meltblown, flashspun and It is a nonwoven fabric by any one method selected from needle punching.

According to the present invention, in a depth filter composed of a multilayer filter layer provided with an asymmetric pore gradient such that the average pore size gradually increases from the inner core to the outer circumferential surface, the asymmetry is maintained by maintaining the same average pore size of the filter medium constituting the filter layer. By maintaining the pore gradient and narrowly controlling the average fiber fineness, it is possible to provide a depth filter having excellent slurry particle removal ability and trapping ability. Thus, the present invention is useful as a depth filter for slurry filtration of the CMP process.

At least one of the multilayer filter layers reduces the fineness of the filter media, thereby increasing the number of porosity and pore size in the deep filter media, thereby improving particle trapping capacity, and increasing the cycle life of the cylindrical depth filter. Can be provided.

Hereinafter, the present invention will be described in more detail.

The present invention consists of a multi-layered media layer which is provided with an asymmetric pore gradient so that the average pore size gradually increases from the inner core to the outer circumferential surface, while maintaining the same average pore size of the media constituting the media layer, the fine fiber fineness becomes finer. It provides a depth filter for slurry filtration of the CMP process having a deep filter.

Preferably, with respect to the average fiber fineness in the average pore diameter of the media in which the finely divided deep media constitutes the median layer, the fineness of the average fiber is 80% or less, more preferably 30, while maintaining the same average pore size. To finer at 60%. At this time, when the fineness control of the average fiber exceeds 80%, it is not expected to improve the slurry particle removal ability or the particle collection efficiency of the medium.

The average pore size of the filter medium may be applied as long as the pore size required by the depth filter is preferably 1 to 30 μm.

In the exemplary embodiment of the present invention, a depth filter composed of a first filter layer, a second filter layer, and a third filter layer made of an asymmetric pore gradient to gradually increase the pore size from the inner core to the outer circumferential surface is described as an example. The present invention is not limited to this, and may comprise a multi-layer media layer composed of at least three media layers having different porosities depending on the fineness of the fibers constituting the media, preferably three to six layers.

In addition, the description is limited to including a depth filter in which the average fiber fineness of the filter media formed by any one of the first filter layer, the second filter layer, and the third filter layer is included. It will of course be understood that depending on the field, two or three layers in the filter layer may constitute a deeper micronized filter.

In the depth filter for slurry filtration of the CMP process of the present invention, while the depth filter maintains the same average pore size, the media volume is formed by using the same fine fiber, the pore size in the depth filter increases. , The number of politeness increases. Therefore, while maintaining the average pore size gradient of the same media, as the average fiber fineness of the media layer decreases, the differential pressure increases as the tortuosity in the media layer increases, but the particle removal performance is improved from high porosity. In particular, the cycle of use increases significantly.

Therefore, the depth filter for slurry filtration of the CMP process of the present invention can control the change in the collection capacity for each particle size by adjusting the fineness of the average fiber constituting the filter media layer, it is possible to adjust the removal efficiency and use cycle of the filter accordingly .

The material used for the media layer of the present invention is made of any one selected from the group consisting of polyethylene, polypropylene, polyester, polyolefin and polyamide, spunbond, heat bond, spunlace, meltblown, flashspun and A nonwoven media produced by any one method selected from needle punching is used.

The present invention provides a method for manufacturing a cylindrical depth filter that sequentially rolls a multi-layered nonwoven media layer to which an asymmetric pore gradient is gradually increased from the inner center to the outer peripheral surface, wherein the multi-layered nonwoven media layer has the same average pore size. While maintaining, the average fiber fineness is provided with a fine-grained depth filter to provide a method for producing a cylindrical depth filter, characterized in that each layer is constituted by the same volume.

More preferably, as the depth filter of the cylindrical depth filter, by using a melt-blown nonwoven fabric having a fineness compared to the same average pore size as before, the number of porosity and pore size in the depth filter can be increased. Compared with the particle collecting ability is excellent, thereby increasing the product life cycle.

The nonwoven media of the present invention is preferably any one polymer material selected from the group consisting of polyethylene, polypropylene, polyester, polyolefin, and polyamide, and the filter is manufactured by arranging and rolling each of the average pores around the core.

The present invention provides a cylindrical depth filter having improved particle removal ability and particle trapping ability by adjusting the fineness of the average fibers of each of the nonwoven media constituting the layer for each pore size in the depth filter.

From the manufacturing method of the present invention, when constructing the nonwoven fabric, the nonwoven fabric having different fineness is designed to gradually increase the average pore size according to the diameter of the filter so that relatively large particles in the outer filter layer and small particles in the filter inner layer are collected. A cylindrical depth filter is provided, wherein each layer has the same average pore size and is replaced by a medium having a smaller average fineness, thereby improving the removal efficiency and collection efficiency of large particles.

The nonwoven media is made of any one selected from the group consisting of polyethylene, polypropylene, polyester, polyolefin and polyamide, and any one selected from spunbond, thermal bonding, spunlace, meltblown, flashspun and needle punching. It is a nonwoven media produced by the method.

Hereinafter, the present invention will be described in more detail with reference to Examples.

This embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

≪ Example 1 >

A depth filter consisting of a total of three filter layers including the first filter, the second filter, and the third filter from the core to the outermost part was fabricated.

Specifically, the first filter layer winds the meltblown filter medium having an average pore size of 4 to 5 μm and an average fiber diameter of 0.5 to 1 μm from the core to a position 1/3 of the depth filter diameter excluding the region of the core. On the first media layer, the second media layer winds the meltblown media with an average pore size of 7 to 9 µm and an average fiber diameter of 2 to 3 µm, and the third media layer is sequentially with an average pore size of 15 to 18 µm and an average fiber diameter. A cylindrical deep filter was manufactured by winding a melt blown medium having a size of 3 to 4 μm to the outermost part in the remaining 2/3 region.

<Example 2>

A depth filter consisting of a total of three filter layers including the first filter, the second filter, and the third filter from the core to the outermost part was fabricated.

The first filter layer winds the meltblown filter medium having an average pore size of 4 to 5 μm and an average fiber diameter of 1 to 2 μm from the core to a position 1/3 of the depth filter diameter excluding the core region. The layer was wound with a melt blown medium having an average pore size of 7 to 9 µm and an average fiber diameter of 1 to 2 µm up to a position of 2/3, and the third media layer was sequentially having an average pore size of 15 to 18 µm and an average fiber diameter of 3 A cylindrical deep filter was manufactured by winding a meltblown filter medium of ˜4 μm to the outermost portion in the remaining 2/3 region.

&Lt; Example 3 >

A depth filter consisting of a total of three filter layers including the first filter, the second filter, and the third filter from the core to the outermost part was fabricated.

The first filter layer winds the meltblown filter medium having an average pore size of 4 to 5 μm and an average fiber diameter of 1 to 2 μm from the core to a position 1/3 of the depth filter diameter excluding the core region. The layer is wound with a melt blown media having an average pore size of 7 to 9 µm and an average fiber diameter of 2 to 3 µm to a position of 2/3, and the third media layer is sequentially having an average pore size of 15 to 18 µm and an average fiber diameter of 2 A cylindrical deep filter was manufactured by winding the meltblown media of ˜3 μm to the outermost portion in the remaining 2/3 region.

&Lt; Comparative Example 1 &

A depth filter consisting of a total of three filter layers including the first filter, the second filter, and the third filter from the core to the outermost part was fabricated.

The first filter layer winds the meltblown filter medium having an average pore size of 4 to 5 μm and an average fiber diameter of 1 to 2 μm from the core to a position 1/3 of the depth filter diameter excluding the core region. The layer was wound with a melt blown medium having an average pore size of 7 to 9 µm and an average fiber diameter of 2 to 3 µm up to a position of 2/3, and the third media layer was sequentially subjected to an average pore size of 15 to 18 µm and an average fiber diameter of 3 A cylindrical deep filter was manufactured by winding a meltblown filter medium of ˜4 μm to the outermost portion in the remaining 2/3 region.

&Lt; Comparative Example 2 &

A depth filter consisting of a total of three filter layers including the first filter, the second filter, and the third filter from the core to the outermost part was fabricated.

The first media layer winds the meltblown media with an average pore size of 4 to 5 µm and an average fiber diameter of 2 to 3 µm from the core to a position 1/3 of the depth filter diameter excluding the core region. The layer is wound with a melt blown medium having an average pore size of 7 to 9 µm and an average fiber diameter of 2 to 3 µm up to a position of 2/3, and the third media layer is sequentially having an average pore size of 15 to 18 µm and an average fiber diameter of 3 A cylindrical deep filter was manufactured by winding a meltblown filter medium of ˜4 μm to the outermost portion in the remaining 2/3 region.

<Experimental Example 1>

Cylindrical depth filters prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were manufactured to a length of 4 inches to prepare test samples, and physical properties were measured as follows.

1. Flow Measurement

The pure water of 18MΩ was filtered, and the treated flow rate according to the initial pressure was measured by a flow meter and expressed as LPM / psi.

2. Measurement of Particle Removal Capacity

The silica slurry was diluted with pure water and administered through a gear pump, and the number of particles having a size of 1.0 μm or more before and after the filter was measured, and the change in the number of particles was expressed as a percentage.

3. Use cycle measurement

Diluting the silica slurry in pure water and administering it through the gear pump, and measuring the time when the differential pressure reaches 5psi, it was analyzed how fast the internal pore closure by the particles over time.

Comparing Example 1 and Comparative Example 1, the design structure and pore size gradient of the media layer are the same, but only by configuring the average fiber fineness of the first media layer with a thin media, the time to reach a differential pressure of 5 psi is increased. Usage cycle was increased, and improved particle removal efficiency was shown.

In addition, compared to Comparative Example 1, Example 2, which has a thinner average fiber fineness of the second filter layer, also increases the use cycle and particle removal efficiency.

In comparison with Comparative Example 1, Example 3, which has a thinner average fiber fineness of the third filter layer, also has an increased use cycle and particle removal efficiency.

In addition, as confirmed in Example 1, Comparative Example 1, and Comparative Example 2, in the formation of the first media layer, while the fineness of the average fiber of the media layer increases while maintaining the average pore size gradient of the same media, the flow rate This slight increase, but the particle removal performance is greatly reduced, the use cycle is also significantly reduced.

From the above, by controlling the fineness of the average fiber constituting the filter medium layer it is possible to control the change in the trapping capacity for each particle size, thereby adjusting the removal efficiency and the use cycle of the filter.

In view of the above, the present invention is composed of a multi-layered media layer to which an asymmetric pore gradient is given so that the average pore gradually increases from the inner core to the outer circumferential surface, while maintaining the same average pore size of the media constituting the media layer. While maintaining the average fiber fineness was provided a depth filter for slurry filtration of the CMP process finely controlled.

At least one of the multilayer filter layers reduces the fineness of the filter media, thereby increasing the number of porosity and pore size in the deep filter media, thereby improving particle trapping capacity, and increasing the cycle life of the cylindrical depth filter. Can be provided.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. .

Claims (7)

It consists of a multi-layer media layer that is given an asymmetric pore gradient so that the average pore size gradually increases from the inner core to the outer circumferential surface.
A depth filter having fineness of 30 to 60% of the fineness of the average fiber with respect to the average fiber fineness of 1 to 40 µm in the average pore size of the filter medium constituting the filter layer while maintaining the same average pore size of the filter medium constituting the filter medium layer. Depth filter for slurry filtration of the CMP process, characterized in that provided with the same volume of the filter medium layer. delete The depth filter for slurry filtration of the said CMP process of Claim 1 whose average pore size of the said media material is 1-30 micrometers. The depth filter for slurry filtration of the CMP process according to claim 1, wherein at least one of the multilayer filter layers is provided as a finely divided deep filter. The depth filter for slurry filtration of the CMP process according to claim 1, wherein the multilayer filter layer is composed of at least three to six layers. The depth filter for slurry filtration of the CMP process according to claim 1, wherein the media layer is a non-woven media composed of any one selected from the group consisting of polyethylene, polypropylene, polyester, polyolefin, and polyamide. The slurry filtering method of the CMP process according to claim 6, wherein the nonwoven media is manufactured by any one method selected from among spunbond, thermal bonding, spunlace, meltblown, flashspun and needle punching. Deep Filter.