CN113977453A - Chemical mechanical polishing pad for improving polishing flatness and application thereof - Google Patents

Chemical mechanical polishing pad for improving polishing flatness and application thereof Download PDF

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Publication number
CN113977453A
CN113977453A CN202111312061.8A CN202111312061A CN113977453A CN 113977453 A CN113977453 A CN 113977453A CN 202111312061 A CN202111312061 A CN 202111312061A CN 113977453 A CN113977453 A CN 113977453A
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polishing
polishing pad
chemical mechanical
microspheres
layer
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CN113977453B (en
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谢毓
王凯
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Wanhua Chemical Group Electronic Materials Co ltd
Wanhua Chemical Group Co Ltd
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Wanhua Chemical Group Electronic Materials Co ltd
Wanhua Chemical Group Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/11—Lapping tools
    • B24B37/20—Lapping pads for working plane surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/11—Lapping tools
    • B24B37/20—Lapping pads for working plane surfaces
    • B24B37/22—Lapping pads for working plane surfaces characterised by a multi-layered structure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/11—Lapping tools
    • B24B37/20—Lapping pads for working plane surfaces
    • B24B37/24—Lapping pads for working plane surfaces characterised by the composition or properties of the pad materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/11—Lapping tools
    • B24B37/20—Lapping pads for working plane surfaces
    • B24B37/26—Lapping pads for working plane surfaces characterised by the shape of the lapping pad surface, e.g. grooved

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
  • Mechanical Treatment Of Semiconductor (AREA)

Abstract

The invention discloses a chemical mechanical polishing pad for improving polishing flatness and application thereof, wherein the surface of a polishing layer of the polishing pad comprises two regions with different micropore sizes: has a small pore region I with a pore diameter of 1-50 μm and a micro pore region II with a pore diameter of 200-1000 nm. The chemical mechanical polishing pad provided by the invention has micropores with special pore size distribution, and can ensure that the optimal surface flatness is obtained and no large scratch is generated under the polishing conditions of more advanced processing and narrower line width.

Description

Chemical mechanical polishing pad for improving polishing flatness and application thereof
Technical Field
The invention belongs to the technical field of chemical mechanical polishing, and particularly relates to a chemical mechanical polishing pad for improving polishing flatness and application thereof.
Background
In the fabrication of integrated circuits and electronic devices, wafer processing, which requires the sequential deposition of layers of materials onto a semiconductor wafer surface, can cause the wafer surface to become uneven, where it is often necessary to smooth and remove the fine irregularities of the semiconductor wafer surface. Chemical mechanical planarization or Chemical Mechanical Polishing (CMP) is a common technique used to planarize or polish workpieces, such as semiconductor wafers. During conventional polishing, a polishing head holds a wafer, the wafer is placed in contact with a polishing layer of a polishing pad, the polishing pad is mounted on a platen, and a carriage assembly provides a controllable pressure between the wafer and the polishing pad. At this point, the polishing medium is dispensed over the polishing pad surface and into the gap between the wafer and the polishing layer. The wafer surface is polished by chemical and mechanical action of the polishing layer and the medium on the wafer surface to achieve planarization.
However, with the development of technology, higher requirements are put on more advanced polishing processes, and the line width of semiconductor etching has gradually been developed to 7nm, 5nm, or even 3 nm. This places higher demands on the polishing flatness of the polishing pad.
Patent CN107813219B resulted in a polyurethane polishing pad, consisting of polyurethane containing hydrophilic moieties in a specific ratio, by selecting a specific formulation, which provides improved defectivity without a corresponding decrease in planarization efficiency.
Patent CN108115554A also discloses a two-component solvent-free and substantially water-free formulation resulting in a polyurethane polishing pad having improved tensile modulus while maintaining desirable elongation and acceptable defectivity performance.
Most of the current methods for improving planarization are to modify the properties of the polishing pad by changing the formulation of the polishing pad, and to add microspheres to the polishing layer, which are generally between 20 and 60 microns in diameter. However, the above methods all have certain disadvantages: the method for adjusting the grinding flatness by changing the formula cannot ensure that other performances cannot be reduced while the grinding flatness is adjusted, and the addition of the microspheres of 20-60 micrometers has limitation on improving the flatness.
Disclosure of Invention
In order to solve the problems of the prior art, an object of the present invention is to provide a chemical mechanical polishing pad with better planarization effect, which can provide higher polishing planarization without causing more scratches when applied to a more advanced process.
It is another object of the present invention to provide use of such a chemical mechanical polishing pad for improving polishing planarity.
In order to achieve the purpose, the invention adopts the following technical scheme:
a chemical mechanical polishing pad for improving polishing flatness is characterized in that a polishing layer of the polishing pad is divided into an I area and a II area, the diameter of the polishing layer is R, and the diameter of the II area is R for a middle circular structure1The I area is an annular structure except the middle circular structure and has the size of R-R1(ii) a Wherein the polishing layer in the area I has a small-hole structure, and the aperture is 1-50 μm; the polishing layer in the zone II has a microporous structure, the pore diameter is 200-1000 nm, and the absolute value of the difference between the porosities of the zone I and the zone II is less than or equal to 3%.
In a specific embodiment, the porosity of the I and II regions is 40-45%.
In a particular embodiment, the polishing layer comprises microspheres that are hollow microspheres or microspheres that comprise a liquid therein; preferably, the percentage of the microspheres in the zone I to the total mass of the polishing layer in the zone I is a%, and the percentage of the microspheres in the zone II to the total mass of the polishing layer in the zone II is b%, which satisfies a < b <2a, preferably, 3. ltoreq. a.ltoreq.6.
In a specific embodiment, the diameter R of the intermediate circular structure in zone II1Satisfy 2/3R ≦ R1≤3/4R。
In a specific embodiment, the difference in compressibility between the polishing surfaces corresponding to zones I and II is 0.5% or less in absolute value.
In a specific embodiment, the absolute value of the difference between the hardness of the polishing surfaces corresponding to the zones I and II is less than or equal to Shore 3D.
In a specific embodiment, the pore structure or microporous structure is approximately spherical.
In a specific embodiment, the surface of the polishing layer is also engraved with grooves of arbitrary shape, and preferably, the polishing pad is a non-foam body.
In a specific embodiment, the polishing pad can be provided with an endpoint detection window as desired, and preferably, the polishing pad further comprises at least a buffer layer and an adhesive layer.
On the other hand, the chemical mechanical polishing pad is preferably used for chemical mechanical planarization of copper wafers, sapphire wafers, silicon wafers, and wafers.
Compared with the prior art, the invention has the following beneficial effects:
the polishing layer of the chemical mechanical polishing pad of the present invention has two pore structure forms, including a microporous region with a pore size of less than 1 μm within the polishing track and a porous region with a pore size of more than 1 μm at the edge of the polishing layer. Compared with the prior common pore diameter structure, the polishing pad has a pore structure with the pore diameter smaller than 1 μm dispersed in the polishing track area, the micropores can be similar to small bowls which are arranged in the polishing layer one by one, the smaller the size of the bowl is, the more the number of the bowls is, the more uniform the polishing medium distributed in the bowls is, and the more uniform the polishing medium in the bowls can be combined with the substrate for polishing; at the same time, the polishing pad has a relatively uniform porosity throughout. If the size of the micropores is too small, the agglomeration of the microparticles is more obvious, and the microparticles cannot be uniformly distributed, so that the uniformity of the polishing pad is affected. If the size of the micropores is too large, excessive grinding particles in the polishing medium will remain in the micropores, and the requirements of electronic devices with higher processing procedures and narrower line widths on polishing flatness cannot be met. The polishing pad is characterized in that a small hole structure with the diameter of 1-50 mu m is arranged in the outer edge area of the polishing pad, so that polishing debris generated after a wafer is polished can not remain between the polishing pad and the wafer to cause scratches on the surface of the wafer, the debris can quickly fall into the small hole on the edge of the polishing layer and flow out of the polishing pad under the action of polishing liquid along with the rotation of the machine table, and the possibility of causing scratches is avoided.
Drawings
FIG. 1 is a schematic diagram of a CMP pad structure for improving polishing planarity according to the present invention.
FIG. 2 is a schematic view of a casting mold for preparing the chemical mechanical polishing pad of the present invention.
Wherein, 1 is a top flat plate, 2 outer walls of the mold, 3 annular regions, 4 cylindrical molds and 5 cylindrical regions.
Detailed Description
The following examples will further illustrate the method provided by the present invention in order to better understand the technical solution of the present invention, but the present invention is not limited to the listed examples, and should also include any other known modifications within the scope of the claims of the present invention.
As shown in FIG. 1, the polishing layer of the polishing pad is divided into two sections, zone I and zone II. The polishing layer has a diameter of R, and the region II has a middle circular structure with a diameter of R1The I area is an annular structure except the middle circular structure and has the size of R-R1Wherein the diameter of the middle circular structure of the polishing layer II area is 2/3R-R1≤3/4R。
The polishing layer in the zone I has a small pore structure, the pore diameter is 1-50 μm, and the size of the small pore is preferably 10-40 μm, such as 10 μm, 20 μm, 30 μm, 40 μm, but not limited thereto; the polishing layer in zone II has a pore structure with a pore diameter of 200-1000 nm, and the pore size is preferably 300-800 nm, such as 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, but not limited thereto.
The polishing layer has a porosity of 40-45%, such as 40%, 41%, 42%, 43%, 44%, 45%, but not limited thereto. Wherein the absolute value of the difference in porosity between zone I and zone II is less than or equal to 3%, preferably less than or equal to 2%, for example 0%, 0.5%, 1%, 1.5%, 2%, but not limited thereto.
In order to keep the porosity of the I area and the II area approximately same, the method is realized by adding microspheres and controlling the adding amount of the microporous microspheres and the microporous microspheres, wherein the density of the microporous microspheres is about 1-3 times of that of the microporous microspheres.
In the polishing layer, the percentage of the microspheres in the zone I to the total mass of the polishing layer in the zone I is a%, wherein a is greater than or equal to 3 and less than or equal to 6, preferably greater than or equal to 4 and less than or equal to 5, and a is, for example, 4, 4.2, 4.4, 4.6, 4.8, 5, but not limited thereto. The percentage of microspheres in zone II to the total mass of the polishing layer in zone II is b%, a is less than or equal to b is less than or equal to 2a, preferably 1.2a is less than or equal to b is less than or equal to 1.8a, and b is selected from the group consisting of, but not limited to, 1.2a, 1.4a, 1.6a, and 1.8 a.
On the polishing layer of the polishing pad, the absolute value of the difference between the compressibility of the polishing surface corresponding to zone I and zone II is 0.5% or less, and the difference between the compressibility is preferably less than 0.3%, for example, 0%, 0.1%, 0.2%, 0.3%, but not limited thereto. The absolute value of the difference between the hardness of the polishing surfaces corresponding to zones I and II is less than or equal to shore 3D, and the difference is preferably less than 2D, such as 0D, 0.5D, 1D, 1.5D, and 2D, but not limited thereto.
The micropores in the polishing layer of the invention can be microspheres incorporated during the synthesis of the polishing pad, for example, a mass flow feed delivery system is used, and the flowability of the microspheres is controlled by the system during the reaction of the polishing layer composition, thereby controlling the uniform distribution of the microspheres in the polishing layer; high shear equipment can also be used to disperse the microspheres in the polishing layer composition using high shear forces. The method of dispersing the microspheres in the polishing layer composition is not limited to the above-described method, and any method known to those skilled in the art may be used in the present invention.
The microspheres in the polishing layer are approximately spherical, preferably spherical; the microspheres may be hollow microspheres or microspheres that contain a liquid therein, wherein the liquid does not react with the polishing layer matrix material and affect the polishing effect, and the preferred liquid is water. Preferably, the microspheres in the polishing layer are hollow microspheres.
The polishing layer surface of the chemical mechanical polishing pad of the present invention also has a groove shape, for example, a groove pattern selected from the group consisting of curved grooves, linear grooves, perforations, and combinations thereof. Preferably, the pattern of grooves comprises a plurality of grooves, such as one selected from the group consisting of: concentric grooves, spiral grooves, cross shadow groove, X-Y grid grooves, hexagonal grooves, triangular grooves, fractal grooves and combinations thereof. Preferably, the polishing pad of the present invention may be provided with an endpoint detection window as needed, and the shape of the window is not particularly limited, and may be, for example, a quadrangle, a triangle, a circle, etc., preferably a rectangle or a square. The end-point detection window can be either an insert type window or a unitary type window, and can be placed within the polishing pad using any of the techniques disclosed in the art.
The polishing layer of the polishing pad of the present invention is a non-foaming material, which may be made of a material commonly used in the art without any limitation, for example, the material of the polishing layer is at least one selected from a segmented block copolymer or a polyurethane elastomer, and preferably is a polyurethane elastomer. For example, the polyurethane elastomer is obtained by reacting a prepolymer containing unreacted isocyanate groups with an alcohol or amine curing agent containing active hydrogen reactive groups. The preferable prepolymer containing unreacted isocyanate groups is obtained by reacting isocyanate with benzene rings with polyether polyol, and the preferable alcohol or amine curing agent containing active hydrogen reaction groups is a polyamine curing agent.
The polishing surface of the polishing layer of the present invention can be treated by any abrading and/or sanding method known to those skilled in the art to open the surface of the microspheres on the surface and thereby create pore openings in the surface of the polishing layer.
The polishing pad at least comprises a buffer layer and a bonding layer. As the buffer layer of the polishing pad, it may be selected from open cell foam materials, woven materials and non-woven materials, including felt materials, woven felt materials and needle punched materials, thick flannel materials, etc., but is not limited thereto. The thickness of the buffer layer is not particularly limited and may be selected from, for example, SUBA series materials.
The adhesive layer is positioned between the polishing layer and the buffer layer and used for bonding the polishing layer and the buffer layer together, and the adhesive layer is selected from at least one of hot melt adhesives or pressure-sensitive adhesives. The hot melt adhesive is selected from at least one of polyolefin, ethylene vinyl acetate, polyamide, polyester, polyurethane, polyvinyl chloride or epoxy resin; the pressure-sensitive adhesive is selected from at least one of a propylene-based adhesive (PSAV) or a rubber-based adhesive (PSA 8). The process of bonding and attaching the polishing layer to the buffer layer via the adhesive layer is not particularly limited, and reference may be made to the prior art, which is well known to those skilled in the art.
The polishing layer of the present invention can be prepared by the following method:
a casting mold is provided as shown in fig. 2. The mould has top flat board 1, is in fixed position and unmovable cylindrical mould outer wall 2, is in activity position detachable cylindrical mould 4, and the circular ring form region 3 has been enclosed jointly to mould outer wall 2 and cylindrical mould 4, has enclosed cylindric region 5 in the cylindrical mould. In the casting process, the mixed composite material is firstly cast into the area 3, after the composite liquid is gelled, the mould 4 is drawn out, and the composite material mixed with the microspheres with smaller aperture is cast into the area 5. And then heating and curing the whole die, and cooling and demolding to obtain the polishing layer structure.
The chemical mechanical polishing pad with optimized grooves of the invention can be applied to chemical mechanical planarization, and is preferably used for chemical mechanical polishing of copper wafers, sapphire wafers and wafers, but is not limited to the above. The polishing method can be referred to the prior art, which is well known to those skilled in the art, and for example, the polishing method comprises the following steps:
providing the chemical mechanical polishing pad;
applying a pressure to the polishing element to press against the polishing pad;
polishing is performed by providing relative motion between the polishing element and the polishing pad.
The invention is further illustrated, but not limited, by the following more specific examples.
The main equipment used in the examples and comparative examples of the present invention are as follows:
polishing equipment: a MirraTMCMP polisher;
the main polishing and testing methods used in the examples and comparative examples of the present invention were as follows:
the polishing method comprises the following steps: a W-plated film (purchased from Sente material, purity 99.95%) is mounted on a polishing head, and an off-line trimming method is adopted under the polishing head pressure of 1.5psi (10.3kPa) and using acidic colloidal silica slurry polishing solution (purchased from the Angstrom technology). The platen speed was 95rpm and the carrier speed was 85rpm during polishing.
And (3) planarization testing: before and after each polishing experiment, the substrate was polished using a Four-point probe (Four Dimensions, Inc,
Figure BDA0003341994540000071
) 81 test points at the same position on the measuring chip of the tester are thickAnd the removal rate RR is calculated from the difference in thickness. The removal rate calculation formula is as follows:
Figure BDA0003341994540000081
wherein the content of the first and second substances,
Figure BDA0003341994540000082
the average of the thicknesses of 81 test points before polishing,
Figure BDA0003341994540000083
is the average value of the thicknesses of 81 test points after polishing, delta TavgThe average value of the thickness difference before and after polishing was obtained for each of the 81 points before and after polishing. The standard deviation of the removal rate was calculated to give a non-uniformity ratio (% NUR). The smaller the non-uniformity ratio, the higher the polishing planarization degree over the entire polishing surface.
Scratch test: and after polishing, scanning the surface of the polishing element by using an electron microscope, and counting the number of scratches with the length of more than 50 nm.
And (3) porosity testing: from the surface of the polishing layer, the machined surface was observed by SEM from the slice to a certain thickness, and the porosity was approximated by calculating the ratio of the area of the micropores to the total area.
And (3) hardness testing: performing Shore hardness test according to the GB/T531-2008 method.
And (3) compression ratio testing: compression ratio testing was performed according to ASTM D1229-2003(2008) method.
And (3) measuring the pore size: average pore size was read using a bench-top scanning electron microscope equipped with the pore size system PoroMetric software.
The main raw materials used in the examples and comparative examples of the present invention were as follows:
prepolymer PHP-75D from prepolymer Air Products and Chemicals, inc;
curing agent MOCA crystal Hao chemical industry;
PSA pressure sensitive adhesive 3M company;
large-pore hollow microspheres: acksonobel, 40D25, average particle size 25 μm, density 0.4g/cm340D45 having an average particle size of 45 μm and a density of 0.4g/cm3(ii) a HOLLOWLITE, hollow microsphere HS65, having an average particle size of less than 20 μm and a density of 0.37g/cm3。
Small pore hollow microspheres: convono biotech Corp., hollow poly-dopamine microspheres with a pore size of 300-400 nm and a density of 0.3g/cm3(ii) a The bamboo science and technology is that hollow glass beads with the aperture of 600-800 nm and the density of 0.26g/cm3(ii) a A sitagliptin biosome having a BWQ-21, a pore size of 900-1000 nm and a density of 0.26g/cm3。
Example 1
Adding 10g of microspheres with the aperture of 25 mu m into a mixed solution of 200g of prepolymer and 48.3g of curing agent through high shear force, uniformly stirring, pouring into a mold area 3, and taking out the mold 4 after 15min of gel formation. Pouring a composition liquid mixed with 12.5g of microspheres with the aperture of 300nm, 235g of prepolymer and 60g of curing agent into a mold 5 to obtain R 13/4R. And (3) putting the die into a 120 ℃ oven for heating and curing for 12h, cooling to room temperature to obtain a polyurethane block, cutting the block into polishing layer sheets by using a slicing machine, and attaching the polishing layer sheets to the SUBA buffer layer through PSA (pressure swing adsorption) to obtain the polishing pad.
Example 2
Adding 13.8g of microspheres with the aperture of 45 mu m into a mixed solution of 237g of prepolymer and 59.6g of curing agent through high shear force, uniformly stirring, pouring into a mold area 3, and taking out the mold 4 after 15min of gel. Pouring a composition liquid mixed with 20.1g of microspheres with the aperture of 600nm, 235g of prepolymer and 60g of curing agent into a mold 5 to obtain R11/2R. And (3) putting the die into a 120 ℃ oven for heating and curing for 12h, cooling to room temperature to obtain a polyurethane block, cutting the block into polishing layer sheets by using a slicing machine, and attaching the polishing layer sheets to the SUBA buffer layer through PSA (pressure swing adsorption) to obtain the polishing pad.
Example 3
Adding microspheres 12.2g and 45 mu m in pore diameter into a mixed solution of 194g of prepolymer and 48.5g of curing agent through high shear force, uniformly stirring, pouring into a mold area 3, and taking out the mold 4 after 15min of gel formation. A composition comprising 28.3g of microspheres having an aperture of 900nm, 240g of a prepolymer and 62.8g of a curing agent was poured into a mold 5 to obtain R 12/3R. Putting the mould into a 120 ℃ oven for heating and curingAnd cooling to room temperature to obtain a polyurethane block, cutting the block into polishing layer sheets by using a slicing machine, and attaching the polishing layer sheets to the SUBA buffer layer through PSA (pressure sensitive adhesive) to obtain the polishing pad.
Comparative example 1
10g of microspheres with the aperture of 25 mu m are added into the mixed solution of 200g of prepolymer and 48.3g of curing agent through high shearing force, evenly stirred and poured into a mold. And (3) putting the die into a 120 ℃ oven for heating and curing for 12h, cooling to room temperature to obtain a polyurethane block, cutting the block into polishing layer sheets by using a slicing machine, and attaching the polishing layer sheets to the SUBA buffer layer through PSA (pressure swing adsorption) to obtain the polishing pad.
Comparative example 2
A mixture of 12.5g of microspheres having a pore size of 300nm, 235g of prepolymer and 60g of curing agent was poured into a mold. And (3) putting the die into a 120 ℃ oven for heating and curing for 12h, cooling to room temperature to obtain a polyurethane block, cutting the block into polishing layer sheets by using a slicing machine, and attaching the polishing layer sheets to the SUBA buffer layer through PSA (pressure swing adsorption) to obtain the polishing pad.
Comparative example 3
Adding 15.7g of microspheres with the aperture of 25 mu m into a mixed solution of 317g of prepolymer and 75g of curing agent through high shear force, uniformly stirring, pouring into a mold area 3, and taking out the mold 4 after 15min of gel formation. A combined solution of 12.4g of microspheres having a pore diameter of 300nm, 235g of a prepolymer and 60g of a curing agent was poured into a mold 5, and R1 was 1/3R. And (3) putting the die into a 120 ℃ oven for heating and curing for 12h, cooling to room temperature to obtain a polyurethane block, cutting the block into polishing layer sheets by using a slicing machine, and attaching the polishing layer sheets to the SUBA buffer layer through PSA (pressure swing adsorption) to obtain the polishing pad.
Comparative example 4
Adding 10g of microspheres with the aperture of 25 mu m into a mixed solution of 200g of prepolymer and 48.3g of curing agent through high shear force, uniformly stirring, pouring into a mold area 3, and taking out the mold 4 after 15min of gel formation. A combined solution of 18.5g of microspheres having a pore diameter of 300nm, 352g of a prepolymer and 89g of a curing agent was poured into a mold 5, and R1 was 4/5R. And (3) putting the die into a 120 ℃ oven for heating and curing for 12h, cooling to room temperature to obtain a polyurethane block, cutting the block into polishing layer sheets by using a slicing machine, and attaching the polishing layer sheets to the SUBA buffer layer through PSA (pressure swing adsorption) to obtain the polishing pad.
Comparative example 5
Adding 10g of microspheres with the aperture of 25 mu m into a mixed solution of 200g of prepolymer and 48.3g of curing agent through high shear force, uniformly stirring, pouring into a mold area 3, and taking out the mold 4 after 15min of gel formation. Pouring a combined liquid mixed with 4.4g of microspheres with the aperture of 300nm, 235g of prepolymer and 60g of curing agent into a mold 5 to obtain R 13/4R. And (3) putting the die into a 120 ℃ oven for heating and curing for 12h, cooling to room temperature to obtain a polyurethane block, cutting the block into polishing layer sheets by using a slicing machine, and attaching the polishing layer sheets to the SUBA buffer layer through PSA (pressure swing adsorption) to obtain the polishing pad.
Example 6
Adding 10g of microspheres with the aperture of 25 mu m into a mixed solution of 200g of prepolymer and 48.3g of curing agent through high shear force, uniformly stirring, pouring into a mold area 3, and taking out the mold 4 after 15min of gel formation. Pouring a composition liquid mixed with 32.5g of microspheres with the aperture of 300nm, 235g of prepolymer and 60g of curing agent into a mold 5 to obtain R 13/4R. And (3) putting the die into a 120 ℃ oven for heating and curing for 12h, cooling to room temperature to obtain a polyurethane block, cutting the block into polishing layer sheets by using a slicing machine, and attaching the polishing layer sheets to the SUBA buffer layer through PSA (pressure swing adsorption) to obtain the polishing pad.
The polishing experiments and tests were carried out using the polishing pads of the examples and comparative examples, respectively, by the methods described previously, and the results are shown in Table 1.
TABLE 1 polishing pad test results data sheet
Figure BDA0003341994540000111
From the data, the chemical mechanical polishing pad prepared according to the invention has low wafer surface non-uniform rate and less scratch number after being subjected to polishing experiments, and can meet the polishing requirements of narrower line width and more advanced processes. In comparative example 1, large-pore microspheres were used in their entirety, and although sufficient storage and removal space was provided for polishing debris, the non-uniformity ratio of the wafer was increased and the polishing planarity was degraded, and similarly, as in comparative example 3, the wafer more contacted the large-pore region within the polishing track, resulting in a degradation of the polishing planarity. In comparative example 2, all the small-pore microspheres were used, and although the non-uniform ratio was low and the grinding flatness was good, since polishing debris and the like had no proper drainage channel, the debris existed on the surface of the polishing pad and the wafer for a long time, and scratches were generated during the polishing process. Similarly, as in comparative example 4, the wafer more contacted the small aperture area within the polishing track, causing a phenomenon in which the number of surface scratches was increased. In comparative examples 5 and 6, since the added mass of the microspheres in zone I and the added mass of the microspheres in zone II do not satisfy the conditions defined in the present invention, the difference in physical properties of the polishing layer corresponding to zone I, II is large, and the polishing characteristics are greatly different, so that the non-uniformity ratio after polishing is high. Meanwhile, the hardness of the area II in the comparative example 5 is high, so that the number of scratches on the surface of the wafer is increased.
While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. It will be appreciated by those skilled in the art that modifications or adaptations to the invention may be made in light of the teachings of the present specification. Such modifications or adaptations are intended to be within the scope of the present invention as defined in the claims.

Claims (10)

1. The chemical mechanical polishing pad for improving polishing flatness is characterized in that a polishing layer of the polishing pad is divided into an I area and a II area, the diameter of the polishing layer is R, the diameter of the II area is R, and the middle circular structure is adopted as the diameter of the II area1The I area is an annular structure except the middle circular structure and has the size of R-R1(ii) a Wherein the polishing layer in the area I has a small-hole structure, and the aperture is 1-50 μm; the polishing layer in the zone II has a microporous structure, the pore diameter is 200-1000 nm, and the absolute value of the difference between the porosities of the zone I and the zone II is less than or equal to 3%.
2. The chemical mechanical polishing pad according to claim 1, wherein the porosity of the zones I and II is 40 to 45%.
3. The chemical mechanical polishing pad according to claim 1 or 2, wherein the polishing layer contains microspheres, the microspheres being hollow microspheres or microspheres containing a liquid therein; preferably, the percentage of the microspheres in the zone I to the total mass of the polishing layer in the zone I is a%, and the percentage of the microspheres in the zone II to the total mass of the polishing layer in the zone II is b%, which satisfies a < b <2a, preferably, 3. ltoreq. a.ltoreq.6.
4. The chemical mechanical polishing pad according to any one of claims 1 to 3, wherein the middle circular structure diameter R of zone II1Satisfy 2/3R ≦ R1≤3/4R。
5. The chemical mechanical polishing pad according to any one of claims 1 to 4, wherein the absolute value of the difference in compressibility between the polishing surfaces corresponding to zones I and II is 0.5% or less.
6. The chemical mechanical polishing pad according to any one of claims 1 to 5, wherein the absolute value of the difference in hardness between the polishing surfaces corresponding to zones I and II is less than or equal to Shore hardness 3D.
7. The chemical mechanical polishing pad according to any one of claims 1 to 6, wherein the small pore structure or the micro pore structure is approximately spherical.
8. The chemical mechanical polishing pad according to any one of claims 1 to 7, wherein the surface of the polishing layer is further grooved with an arbitrary shape, and preferably the polishing pad is a non-foam body.
9. The chemical mechanical polishing pad according to any one of claims 1 to 8, wherein the polishing pad is provided with an endpoint detection window as required, and preferably, the polishing pad further comprises at least a buffer layer and an adhesive layer.
10. Use of the chemical mechanical polishing pad according to any one of claims 1 to 9 for chemical mechanical planarization, preferably for chemical mechanical polishing of copper wafers, sapphire wafers, silicon wafers.
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