JP2012089599A - Chemical mechanical polishing pad and chemical mechanical polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical mechanical polishing pad which can combine enhancement of planarity of a polished surface and reduction of polishing defects (scratch) in the CMP, and to provide a chemical mechanical polishing method using the chemical mechanical polishing pad.SOLUTION: The chemical mechanical polishing pad has a polishing layer formed of a plurality of layers. The polishing layer has at least a first layer having a polishing surface that comes in contact with a polished article when chemical mechanical polishing is performed, and a second layer that is in contact with the first layer on the surface facing the polishing surface of the first layer. The duro D hardness (D1) of the first layer measured after immersing into water of 23°C for one hour and the duro D hardness (D2) of the second layer measured without immersing into water satisfy a relation D1<D2.

Description

  The present invention relates to a chemical mechanical polishing pad and a chemical mechanical polishing method using the chemical mechanical polishing pad.

  In recent years, integration of large-scale integrated circuits (LSIs) typified by semiconductor memories has progressed, and accordingly, the manufacturing technology of large-scale integrated circuits has also increased in density. Furthermore, with this increase in density, the number of stacked semiconductor device manufacturing locations has also increased. And the unevenness | corrugation of the semiconductor wafer main surface which arises by the increase in the number of lamination | stacking is a problem.

  In the manufacture of semiconductor devices, chemical mechanical polishing (hereinafter, also referred to as “CMP”) has attracted attention as a method for forming a flat surface. In CMP, the surface of a wafer on which elements and wirings are formed is slid against each other while being pressed against the polishing layer of the chemical mechanical polishing pad. It is a technique to perform. In this CMP, it is known that the polishing rate, scratches on the surface to be polished, in-plane uniformity, and the like vary greatly depending on the properties and characteristics of the chemical mechanical polishing pad.

  As the chemical mechanical polishing pad, for example, a chemical mechanical polishing pad made of a foamed resin such as polyurethane foam (for example, see Patent Document 1), or a chemical mechanical polishing pad in which water-soluble particles are dispersed in a non-foamed matrix (for example, Patent Document 2) is used. In addition, a technique for reducing polishing scratches (scratches) due to polishing dust or the like by making the polishing pad surface flexible is disclosed (for example, see Patent Document 3). On the other hand, a technique for improving flatness by using a polishing pad provided with a laminated polishing layer in which materials having different hardnesses are laminated is disclosed (for example, see Patent Documents 4 to 7).

JP-A-11-70463 JP 2000-34416 A JP 2003-332277 A JP 10-138123 A JP 2000-202763 A International Publication No. 2002/43921 Pamphlet JP 2004-106177 A

  For example, the chemical mechanical polishing pad described in Patent Document 3 wraps polishing scraps and the like with the surface of a flexible polishing layer, thereby preventing the surface to be polished and the polishing scraps from being pressed with a strong pressure, As a result, the occurrence of polishing scratches (scratches) can be reduced. However, this chemical mechanical polishing pad cannot easily improve the flatness of the object to be polished because the surface of the polishing layer is easily deformed following the unevenness of the object to be polished.

  In addition, the chemical mechanical polishing pads described in Patent Documents 4 to 7 can improve the flatness of the object to be polished by increasing the hardness of the layer having the polishing surface in contact with the object to be polished. However, in these chemical mechanical polishing pads, polishing scratches (scratches) may occur due to polishing debris or the like entering between the object to be polished and the layer having the polishing surface.

  Therefore, some aspects according to the present invention provide a chemical mechanical polishing pad capable of achieving both improvement in flatness of a surface to be polished in CMP and reduction in polishing defects (scratches) by solving the above-described problems, And a chemical mechanical polishing method using the chemical mechanical polishing pad.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
One aspect of the chemical mechanical polishing pad according to the present invention is:
A chemical mechanical polishing pad comprising a polishing layer formed from a plurality of layers,
The polishing layer includes a first layer having a polishing surface that comes into contact with an object to be polished when chemical mechanical polishing is performed, a second layer in contact with the first layer on a surface opposite to the polishing surface of the first layer, Having at least
The relationship between the Duro D hardness (D1) measured after immersing the first layer in water at 23 ° C. for 1 hour and the Duro D hardness (D2) measured without immersing the second layer in water is D1. <D2.

[Application Example 2]
In the chemical mechanical polishing pad of Application Example 1, the value of D1 may be 30D or more and 60D or less.

[Application Example 3]
In the chemical mechanical polishing pad of Application Example 1 or Application Example 2, the value of D2 may be 50D or more and 85D or less.

[Application Example 4]
In the chemical mechanical polishing pad of any one of Application Examples 1 to 3, the value of D1 (D1 / D2) with respect to the value of D2 may be 0.5 or more and 0.9 or less.

[Application Example 5]
In the chemical mechanical polishing pad of any one of Application Examples 1 to 4, the first layer may include water-soluble particles.

[Application Example 6]
One aspect of the chemical mechanical polishing method according to the present invention is:
Chemical mechanical polishing is performed using the chemical mechanical polishing pad described in any one of Application Examples 1 to 5.

  According to the chemical mechanical polishing pad according to the present invention, since the durro D hardness of the second layer not exposed to the slurry is larger than the durro D hardness of the first layer exposed to the slurry in CMP, The global deformation of the first layer can be mitigated. As a result, the flatness of the object to be polished can be improved. In addition, since the polishing surface of the first layer can be made softer than the second layer, the surface to be polished and the polishing debris etc. can be applied with a strong pressure by wrapping polishing debris etc. in the flexible polishing surface of the first layer. The pressing can be avoided, and the occurrence of polishing scratches can be reduced.

It is sectional drawing which shows typically the chemical mechanical polishing pad which concerns on this Embodiment. It is a schematic diagram for demonstrating the concept of the duro D hardness in a grinding | polishing layer. It is an enlarged view of the area | region I in FIG. It is a top view which shows typically the chemical mechanical polishing pad which concerns on this Embodiment. It is a top view which shows typically the chemical mechanical polishing pad which concerns on a 1st modification. It is a top view which shows typically the chemical mechanical polishing pad which concerns on a 2nd modification.

  Hereinafter, preferred embodiments of the present invention will be described in detail. In this specification, the term “hardness” simply refers to duro D hardness.

1. Chemical mechanical polishing pad The structure of the chemical mechanical polishing pad according to the present embodiment is not particularly limited as long as it has a polishing layer on at least one surface. The polishing layer is formed of a plurality of layers, and has a first layer having a surface (hereinafter also simply referred to as “polishing surface”) that comes into contact with an object to be polished when chemical mechanical polishing is performed, and the first layer. And a second layer in contact with the first layer on a surface facing the polishing surface. Hereinafter, the chemical mechanical polishing pad according to the present embodiment will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view schematically showing a chemical mechanical polishing pad according to the present embodiment. As shown in FIG. 1, the chemical mechanical polishing pad 100 according to the present embodiment includes a polishing layer 10 and a support layer 20 formed on a surface in contact with the polishing apparatus surface plate 30.

1.1. Polishing Layer As shown in FIG. 1, the polishing layer 10 includes a first layer 12 having a polishing surface 11, a second layer 13 in contact with the first layer 12 on a surface facing the polishing surface 11 of the first layer 12, and At least. Another layer constituting the polishing layer may be further provided on the back surface of the second layer 13 (the surface facing the surface in contact with the first layer 12). Further, the polishing surface 11 of the first layer 12 may be provided with a recess as described later.

  Note that the polishing layer 10 shown in FIG. 1 is a laminated structure obtained by integrally molding two or more layers of different materials. Here, a laminated structure in which two or more layers of different materials are integrally formed is directly bonded by heating and / or pressing without bonding layers of different materials using a double-sided tape or an adhesive. A structure. Therefore, since the laminated structure of the polishing layer 10 and the support layer 20 is a laminated structure bonded using a double-sided tape or an adhesive as will be described later, it is clearly distinguished from the polishing layer.

  When the material constituting the first layer 12 and the material constituting the second layer 13 have a high affinity, the boundary between the first layer 12 and the second layer 13 is formed by integral molding by heating and / or pressing. Although it may be unclear, the polishing layer 10 may have such a configuration. Further, the polishing layer 10 may be composed of a gradient material in which the material from the polishing surface 11 to the back surface thereof continuously changes.

  The first layer 12 has a function of performing chemical mechanical polishing by allowing slurry to flow down on the polishing surface 11 while sliding the wafer surface on which the elements and wirings are formed against the polishing surface 11. . On the other hand, the second layer 13 has a function of mitigating global deformation that occurs when the wafer surface on which elements and wirings are formed is pressed against the polishing surface of the first layer 12.

  The material of the first layer 12 and the second layer 13 constituting the polishing layer 10 is not particularly limited as long as it satisfies the relationship of Duro D hardness described later. For example, thermoplastic obtained by reacting isocyanate and polyol Crosslinking of polyurethane, butadiene rubber, 1,2-polybutadiene, isoprene rubber, acrylic rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber, ethylene-propylene rubber, silicone rubber, fluorine rubber, styrene-isoprene rubber, etc. Rubber etc. are mentioned. Among these crosslinked rubbers, those crosslinked with an organic peroxide are preferable, and 1,2-polybutadiene is more preferable. When 1,2-polybutadiene is used, a rubber having a higher hardness than other crosslinked rubbers can be easily obtained.

  The first layer 12 having the polished surface 11 may contain dispersed water-soluble particles. When the water-soluble particles are contained in the first layer 12, the polishing surface 11 is exposed to the slurry, so that the water-soluble particles are released from the polishing surface 11 and can hold the slurry. ) Is formed. Since the slurry is held by the holes, the polishing performance of the polishing layer 10 can be improved.

  Examples of such water-soluble particles include organic water-soluble particles and inorganic water-soluble particles. Examples of the organic water-soluble particles include saccharides (polysaccharides such as starch, dextrin and cyclodextrin, lactose, mannitol, etc.), celluloses (hydroxypropylcellulose, methylcellulose, etc.), proteins, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic. Examples include acids, polyethylene oxide, sulfonated polyisoprene, and sulfonated isoprene copolymers. Examples of the inorganic water-soluble particles include potassium acetate, potassium nitrate, potassium carbonate, potassium hydrogen carbonate, potassium bromide, potassium phosphate, potassium sulfate, magnesium sulfate, and calcium nitrate. These water-soluble particles may be used alone or in combination of two or more.

  The average particle size of the water-soluble particles is preferably 0.5 to 200 μm. The size of the pores formed when the water-soluble particles are released from the polishing layer surface of the chemical mechanical polishing pad is preferably 0.1 to 500 μm, more preferably 0.5 to 200 μm. When the average particle diameter of the water-soluble particles is within the above range, a chemical mechanical polishing pad having a polishing layer exhibiting a high polishing rate and excellent mechanical strength can be produced.

  The content of the water-soluble particles is preferably 3 to 150 parts by mass with respect to 100 parts by mass of the thermoplastic polyurethane or the crosslinked rubber. When the content of the water-soluble particles is within the above range, a chemical mechanical polishing pad having a high polishing rate in chemical mechanical polishing and having appropriate hardness and other mechanical strength can be produced.

  In the chemical mechanical polishing pad 100, the Duro D hardness measured after immersing the first layer 12 in water at 23 ° C. for 1 hour is defined as D1, and the Duro D hardness measured without immersing the second layer 13 in water. In the case of D2, the relationship D1 <D2 is established.

  The measurement conditions are set as follows. The polishing surface 11 of the first layer 12 is exposed to the slurry during chemical mechanical polishing. On the other hand, since the second layer 13 is sandwiched between the first layer 12 and the support layer 20, it is hardly exposed to the slurry. Therefore, in order to reproduce the state of the polishing layer 10 during actual CMP, the first layer 12 immersed in water at 23 ° C. for 1 hour is prepared, and the duro D hardness (D1) is measured. This is because it is considered that the second layer 13 that is not immersed is prepared and the Duro D hardness (D2) is measured, and then those values are compared.

  When D1 <D2, it is possible to mitigate global deformation of the first layer 12 by the second layer 13 against global indentation deformation of the polishing surface 11 of the first layer 12. Thereby, since the flatness of the whole polishing layer 10 is maintained, the flatness of the object to be polished can be improved. In addition, since the hardness of the polishing surface 11 of the first layer 12 can be made lower than that of the second layer 13, the surface to be polished and the polishing dust can be obtained by wrapping polishing debris etc. in the flexible polishing surface of the first layer 12. And the like can be avoided from being pressed with a strong pressure, and the generation of polishing scratches (scratches) can be reduced.

  On the other hand, if D1 ≧ D2, the second layer 13 is also globally deformed following the global indentation deformation of the polishing surface 11 of the first layer 12. Therefore, the flatness of the entire polishing layer 10 cannot be maintained, and the flatness of the object to be polished is difficult to obtain. Further, since the polishing surface 11 of the first layer 12 has a hardness equal to or higher than that of the second layer 13, the surface to be polished and the polishing scraps may be pressed with a strong pressure to cause polishing scratches (scratches). .

  The duro D hardness (D1) measured after immersing the first layer 12 in water at 23 ° C. for 1 hour is preferably 30D or more and 60D or less, and more preferably 35D or more and 50D or less. When the Duro D hardness (D1) is within the above range, the polishing surface and the polishing debris can be prevented from being pressed with a strong pressure by wrapping the polishing debris with the polishing surface 11 of the first layer 12, and polishing. The effect of reducing the occurrence of scratches (scratches) is higher.

  The Duro D hardness (D2) measured without immersing the second layer 13 in water is preferably 50D or more and 85D or less, and more preferably 60D or more and 80D or less. The pressure when pressing a wafer on which an element or wiring to be polished is pressed against the polishing surface 11 of the first layer 12 is naturally limited in consideration of damage of the wafer. If the Duro D hardness (D2) is within the above range, the global indentation deformation of the first layer 12 can be mitigated even if the limit pressing pressure is applied to the wafer, and the flatness of the object to be polished is maintained. Is done.

  In the chemical mechanical polishing pad 100 according to the present embodiment, the value of D1 (D1 / D2) with respect to the value of D2 is preferably 0.5 or more and 0.9 or less, and is 0.6 or more and 0.8 or less. It is more preferable that When D1 / D2 is within the above range, the balance of duro D hardness between the first layer and the second layer is optimal, and it is possible to achieve both improvement of the flatness of the workpiece and reduction of scratches (scratches). It becomes easy.

  FIG. 2 is a schematic diagram for explaining the concept of duro D hardness in the polishing layer. When a weight is applied to the polishing layer 10 from above by simulating a polishing step as shown in FIG. 2A, the polishing layer 10 is bent as shown in FIG. The durro D hardness is an index indicating the degree of macro deflection of the polishing layer 10 when a weight is applied in the polishing step.

  In the present invention, the duro D hardness of the polishing layer can be measured by a method based on “JIS K6253”. Specifically, the test piece is placed on a flat and solid surface, the pressure plate of the type D durometer is maintained parallel to the surface of the test piece, and the push needle is perpendicular to the surface of the test piece. Holding the type D durometer, the pressure plate is brought into contact with the test piece so as not to give an impact. The tip of the needle is measured at a position 12 mm or more away from the end of the test piece. After the pressure plate is brought into contact with the test piece, reading is performed 15 seconds later. The number of measurement points is measured 5 times at a position separated by 6 mm or more, and the median value is defined as Duro D hardness.

  The duro D hardness (D1) of the first layer 12 can be measured as follows. First, 23 degreeC water is put into a container. Next, the test piece of the first layer 12 is immersed in the water for 1 hour. The Duro D hardness (D1) is obtained by measuring the test piece by the method described above.

  The duro D hardness (D2) of the second layer 13 can be measured as follows. First, when there is a layer that is not integrally molded, such as a subpad, these added layers are peeled off. Furthermore, the 1st layer 12 and the 2nd layer 13 are peeled off by means, such as cutting, and the test piece of the 2nd layer 13 is produced. The Duro D hardness (D2) is obtained by measuring the test piece by the method described above.

  The planar shape of the polishing layer 10 is not particularly limited, but may be, for example, a circular shape. When the planar shape of the polishing layer 10 is circular, the size is preferably 150 mm to 1200 mm in diameter, and more preferably 500 mm to 1000 mm in diameter. The thickness of the polishing layer 10 is preferably 0.5 mm to 5.0 mm, more preferably 1.0 mm to 4.0 mm, and particularly preferably 1.5 mm to 3.5 mm. The thickness of the first layer 12 is preferably 0.1 mm to 1.0 mm, more preferably 0.1 mm to 0.5 mm. The thickness of the second layer 13 is preferably 1.0 mm to 3.0 mm, more preferably 1.5 mm to 2.8 mm. It is preferable for the thickness of each layer to be in the above-mentioned range because deformation of the polishing surface with respect to the object to be polished is optimized, and both improvement in flatness of the object to be polished and reduction of polishing scratches (scratches) can be achieved. The ratio of the thickness of the first layer 12 to the thickness of the second layer 13 (the thickness of the first layer 12 / the thickness of the second layer 13) is preferably 0.03 to 0.5, more preferably 0.03 to 0.2. When the ratio of the thicknesses of the respective layers is within the above range, the deformation of the polishing surface with respect to the object to be polished is optimized, and both improvement in flatness of the object to be polished and reduction of polishing scratches (scratches) can be achieved. preferable.

  FIG. 3 is an enlarged view of region I in FIG. 1, and is a cross-sectional view schematically showing the detailed shape of the polishing layer 10. As shown in FIG. 3, it is preferable that the polishing surface is provided with a plurality of recesses 16. The recess 16 holds slurry supplied during chemical mechanical polishing, distributes it evenly on the polishing surface, and temporarily retains waste such as polishing debris and used slurry and discharges it to the outside. It has a function as a route for

  The cross-sectional shape of the recess 16 is not particularly limited, and may be, for example, a shape formed from flat side surfaces and a bottom surface, a polygonal shape, a U shape, a V shape, or the like. The depth a of the recess 16 is preferably 0.1 mm or more, more preferably 0.1 mm to 2.5 mm, and particularly preferably 0.2 mm to 2.0 mm. The width b of the recess 16 can be 0.1 mm or more, more preferably 0.1 mm to 5.0 mm, and particularly preferably 0.2 mm to 3.0 mm. In the polishing surface, the interval c between the adjacent recesses 16 is preferably 0.05 mm or more, more preferably 0.05 mm to 100 mm, and particularly preferably 0.1 mm to 10 mm. The pitch d, which is the sum of the width of the recess and the distance between adjacent recesses, is preferably 0.15 mm or more, more preferably 0.15 mm to 105 mm, and particularly preferably 0.6 mm to 13 mm. it can. By forming the recess 16 having the shape in the above range, a chemical mechanical polishing pad having an excellent effect of reducing scratches on the surface to be polished and having a long life can be easily manufactured.

  Each preferred range can be a combination of each. That is, for example, it is preferable that the depth a is 0.1 mm or more, the width b is 0.1 mm or more, the interval c is 0.05 mm or more, the depth a is 0.1 mm to 2.5 mm, and the width b is 0. More preferably, the thickness c is 0.05 mm to 100 mm, the depth a is 0.2 mm to 2.0 mm, the width b is 0.2 mm to 3.0 mm, and the distance c is 0.00 mm. 1 mm to 10 mm is particularly preferable.

  The surface roughness (Ra) of the inner surface of the recess 16 is preferably 1 μm or more and 10 μm or less. If the surface roughness (Ra) of the inner surface of the recess 16 is in the above range, it can be said that there is substantially no unevenness on the inner surface of the recess 16 that causes scratches during chemical mechanical polishing. In the case where there are irregularities, particularly large convex portions (for example, uncut parts that occur when the concave portions 16 are formed) on the inner surface of the concave portions 16, the convex portions are detached during chemical mechanical polishing, so that May cause scratches. Furthermore, foreign matters formed by the depressed convex portions being compressed by pressure or frictional heat during polishing, etc., desorbed convex portions and polishing debris, solid content in the slurry, etc. Scratches can also be caused by foreign matter formed. In addition, the convex portion may be detached during dressing to cause the same problem.

  Further, when the surface roughness (Ra) of the inner surface of the recess 16 is in the above range, in addition to preventing scratches, the function as the recess, in particular, the function of distributing the slurry to the polishing surface and the waste are discharged to the outside. The function to perform is demonstrated efficiently.

  The surface roughness (Ra) of the inner surface of the recess can be measured as follows. First, with respect to an arbitrary portion of the inner surface of the recess provided in the polishing layer 10 of the chemical mechanical polishing pad before use, using a surface roughness measuring machine (for example, “SURFTEST” manufactured by Mitutoyo Corporation), the speed is 0. The roughness curve of 5 sections is measured twice in the longitudinal direction and the transverse direction under the conditions of 0.5 mm / s and a reference length of 0.8 mm. From the obtained roughness curve, the average of the absolute values of deviations from the average line to the measurement curve is defined as the surface roughness (Ra) of the inner surface of the recess.

  FIG. 4 is a plan view of the chemical mechanical polishing pad 100 according to the present embodiment. As shown in FIG. 4, the recess 16 can be formed in a plurality of concentric circles whose diameter gradually increases from the center of the polishing surface 11 toward the outer edge.

  FIG. 5 is a plan view of a chemical mechanical polishing pad 200 according to the first modification, and corresponds to FIG. The chemical mechanical polishing pad 200 according to the first modification further includes a plurality of recesses 17 and recesses 18 extending radially from the center of the polishing surface 11 toward the outer edge in addition to the plurality of recesses 16 provided in an annular shape. It differs from the polishing layer 10 in that it includes. Here, the center portion refers to a region surrounded by a circle having a radius of 50 mm with the center of gravity of the polishing layer as the center. The concave portion 17 and the concave portion 18 need only extend from an arbitrary position in the “center portion” in the outer edge direction, and the shape thereof may be, for example, a linear shape, an arc shape, or a combination thereof. The cross-sectional shapes of the recess 17 and the recess 18 can be the same as the recess 16 described above. Since the other configuration of the chemical mechanical polishing pad 200 according to the first modification is the same as the configuration of the polishing layer 10 described with reference to FIGS. 1 and 3, the description thereof is omitted.

  FIG. 6 is a plan view of a chemical mechanical polishing pad 300 according to the second modification, and corresponds to FIG. The chemical mechanical polishing pad 300 according to the second modified example further includes a plurality of recesses 19 that extend radially from the center of the polishing surface 11 toward the outer edge in addition to the plurality of recesses 16 provided in an annular shape. Different from the polishing layer 10 described above. The cross-sectional shape of the recess 19 can be the same as the recess 16 described above. Other configurations of the chemical mechanical polishing pad 300 according to the second modification are the same as the configurations of the polishing layer 10 described with reference to FIGS.

  Although the planar shape of the concave portion has been described above, the planar shape of the concave portion is not particularly limited to the above-described embodiment, and can be appropriately optimized depending on the object to be polished. The planar shape of the recess may be, for example, a polygonal shape such as a triangle, a quadrangle, or a pentagon, an ellipse, or a spiral. Further, the number of recesses provided on the polishing surface is not particularly limited.

1.1.2. Support Layer The support layer 20 is used for supporting the polishing layer 10 on the polishing apparatus surface plate 30 in the chemical mechanical polishing pad 100. Therefore, if the polishing layer 10 can support the polishing apparatus surface plate 30 alone, the support layer 20 may not be provided. The support layer 20 may be an adhesive layer or a cushion layer having the adhesive layer on both sides.

  The adhesive layer can be made of, for example, an adhesive sheet. The thickness of the pressure-sensitive adhesive sheet is preferably 50 μm to 250 μm. By having a thickness of 50 μm or more, the pressure from the polishing surface 11 side of the polishing layer 10 can be sufficiently relaxed, and by having a thickness of 250 μm or less, the influence of unevenness on the polishing performance is not affected. A chemical mechanical polishing pad 100 having a uniform thickness is obtained.

  The material of the pressure-sensitive adhesive sheet is not particularly limited as long as the polishing layer 10 can be fixed to the polishing apparatus surface plate 30, but is preferably an acrylic or rubber-based material having a lower elastic modulus than the polishing layer 10.

  The adhesive strength of the pressure-sensitive adhesive sheet is not particularly limited as long as the chemical mechanical polishing pad can be fixed to the surface plate for a polishing apparatus. However, when the adhesive strength of the pressure-sensitive adhesive sheet is measured according to the standard of “JIS Z0237”, the adhesive strength is preferable. Is 3 N / 25 mm or more, more preferably 4 N / 25 mm or more, and particularly preferably 10 N / 25 mm or more.

  As long as the cushion layer is made of a material having a durometer D lower than that of the polishing layer 10, the material is not particularly limited, and may be a porous body (foam) or a non-porous body. As a cushion layer, the layer which shape | molded foamed polyurethane etc. is mentioned, for example. The thickness of the cushion layer is preferably 0.1 mm to 5.0 mm, more preferably 0.5 mm to 2.0 mm.

2. Method for Producing Chemical Mechanical Polishing Pad The method for producing the polishing layer constituting the chemical mechanical polishing pad according to the present embodiment is not particularly limited as long as the above-described relationship between the duro D hardness of the first layer and the second layer is satisfied. As a specific manufacturing method, for example, a sheet-like molded body constituting the first layer or the second layer of the polishing layer is produced using a general sheet molding method, and the two types of sheet-like molded bodies are fused. A method of obtaining a laminated structure by wearing is mentioned. As a general sheet molding method, a resin composition heated and plasticized at 120 ° C. to 230 ° C. is cooled and solidified by a press machine or an injection molding machine, and plasticized / extruded using an extruder equipped with a T die. A method for forming a sheet is mentioned. The duro D hardness can be controlled by appropriately adjusting the molding conditions.

  The polishing layer thus obtained may form a recess in the polishing surface by cutting. Further, by using a mold in which a pattern to be a recess is formed in advance, the resin composition is molded to form the recess in the polishing layer together with the outer shape of the polishing layer.

3. Chemical Mechanical Polishing Method The chemical mechanical polishing method according to the present embodiment is characterized in that chemical mechanical polishing is performed using the chemical mechanical polishing pad described above. That is, according to the chemical mechanical polishing method according to the present embodiment, the durro D hardness of the second layer not exposed to the slurry is more than the durro D hardness of the first layer exposed to the slurry during chemical mechanical polishing. Therefore, global deformation of the first layer can be mitigated by the second layer. As a result, the flatness of the object to be polished can be improved. In addition, since the polishing surface of the first layer can be made softer than the second layer, the surface to be polished and the polishing debris etc. can be applied with a strong pressure by wrapping polishing debris etc. in the flexible polishing surface of the first layer. The pressing can be avoided, and the occurrence of polishing scratches can be reduced.

  In the chemical mechanical polishing method according to the present embodiment, a commercially available chemical mechanical polishing apparatus can be used. Examples of commercially available chemical mechanical polishing apparatuses include, for example, model “EPO-112”, model “EPO-222” (manufactured by Ebara Corporation); model “LGP-510”, model “LGP-552” (and above, Wrap master SFT); model “Mirra” (Applied Materials) and the like.

  Further, as the slurry, an optimal one can be appropriately selected according to the object to be polished (copper film, insulating film, low dielectric constant insulating film, etc.).

4). Examples Hereinafter, embodiments of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

4.1. Production example of sheet-like molded body 4.1.1. Sheet-like molded product (RB-1)
1,2-polybutadiene (manufactured by JSR Corporation, Duro D hardness 47D, trade name “RB830”) in 80 parts by volume, β-cyclodextrin (Shisui Port Seika Co., Ltd., trade name “Dexipal β-100”, average grain (20 μm in diameter) 20 parts by volume and a composition obtained by kneading 0.3 parts by volume of an organic peroxide (manufactured by NOF Corporation, trade name “Park Mill D-40”) were compressed at 170 ° C. in a press mold. A cylindrical sheet-like molded body (RB-1) having a diameter of 845 mm and a thickness of 1.6 mm was produced.

4.1.2. Sheet shaped product (RB-2)
1,100 per part by volume of 1,2-polybutadiene (manufactured by JSR Corporation, Duro D hardness 32D, trade name “RB810”), organic peroxide (trade name “Park Mill D-40”, manufactured by NOF Corporation) 0 After obtaining a composition in which 3 parts by volume were kneaded, compression molding was performed at 170 ° C. in a press mold to prepare a cylindrical sheet-like molded body (RB-2) having a diameter of 845 mm and a thickness of 1.6 mm.

4.1.3. Sheet-like molded product (RB-3)
In the production example of “4.1.2. Sheet-like molded body (RB-2)”, the addition amount of organic peroxide (trade name “Park Mill D-40” manufactured by NOF Corporation) is 0.12 volume. A sheet-like molded body (RB-3) having the same shape was produced in the same manner except that the part was used.

4.1.4. Sheet shaped product (PU-1)
Thermoplastic polyurethane (trade name “Elastolan 1180A” manufactured by BASF Corporation) is compression-molded at 170 ° C. in a press mold, and a cylindrical sheet-like molded body (PU-1) having a diameter of 845 mm and a thickness of 1.6 mm Produced.

4.1.5. Sheet shaped product (PU-2)
Thermoplastic polyurethane (trade name “Elastollan 1174D” manufactured by BASF Corporation) is compression-molded at 170 ° C. in a press mold, and a cylindrical sheet-like molded body (PU-2) having a diameter of 845 mm and a thickness of 1.6 mm Produced.

4.1.6. Sheet shaped product (PU-3)
In an air atmosphere, 62 parts by mass of polyoxyethylene bisphenol A ether (manufactured by NOF Corporation, trade name “Uniol DA400”) was charged into a 2 L four-necked separable flask equipped with a stirrer, and the temperature was increased to 40 ° C. The temperature was adjusted and stirred. Next, 38 parts by mass of 4,4′-diphenylmethane diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name “MILLIONATE MT”) dissolved in an oil bath at 80 ° C. was added to the flask, and the mixture was stirred and mixed for 15 minutes. Next, the obtained mixture was spread on a SUS vat whose surface was processed, allowed to react at 110 ° C. for 1 hour, and annealed at 80 ° C. for 16 hours to obtain a thermoplastic polyurethane. This thermoplastic polyurethane was compression-molded in a press mold at 170 ° C. to prepare a cylindrical sheet-like molded body (PU-3) having a diameter of 845 mm and a thickness of 1.6 mm.

4.2. Production example of chemical mechanical polishing pad 4.2.1. Example 1
The sheet-shaped molded body (RB-1) and the sheet-shaped molded body (RB-2) were superposed and compressed at 180 ° C. in the mold and integrally molded. This integrally formed laminated sheet is polished with sandpaper, the thickness is adjusted, and a concentric circle having a width of 0.5 mm, a pitch of 1.5 mm, and a depth of 1.0 mm is further obtained by a cutting machine (manufactured by Kato Machine Co., Ltd.) Polishing with a diameter of 600 mm and a thickness of 2.5 mm using a sheet-shaped molded body (RB-1) as a first layer and a sheet-shaped molded body (RB-2) as a second layer by forming a recess and cutting the outer periphery. A layer was obtained. A double-sided tape # 422JA (manufactured by 3M) was laminated on the back surface (the surface on which the concave portion was not formed) of the polishing layer prepared in this manner to prepare a chemical mechanical polishing pad.

4.2.2. Examples 2-5, Comparative Examples 1-4
A chemical mechanical polishing pad was produced in the same manner as in Example 1 except that the material constituting the polishing layer was changed as shown in Table 1.

4.2.3. Comparative Example 5
A commercially available chemical mechanical polishing pad (manufactured by ROHM & HAAS, trade name “IC1000”, a polishing layer made of thermally crosslinked polyurethane resin) was used.

4.3. Measuring method of Duro D hardness A test piece is prepared from a sheet-like molded body as the first layer of the polishing layer, and the test piece is immersed in water at 23 ° C. for 1 hour, and then a hardness measuring machine according to JIS K6253. (Durometer D hardness of the test piece was measured by Excel Corporation, model “Durometer RH-201AD”).

  In addition, a test piece was prepared from a sheet-like molded body as the second layer of the polishing layer, and the test piece was not immersed in water. RH-201AD "), and the Duro D hardness of the test piece was measured. The measurement results of the obtained duro D hardness are also shown in Table 1.

  In addition, in the commercially available chemical mechanical polishing pad of Comparative Example 5, after peeling the double-sided tape affixed to the back surface, a test piece was prepared and the duro D hardness of the first layer and the second layer was measured. did. The results of the obtained Duro D hardness are also shown in Table 1.

4.4. Evaluation of Chemical Mechanical Polishing The chemical mechanical polishing pad produced in “4.2. Example of manufacturing chemical mechanical polishing pad” is attached to a chemical mechanical polishing apparatus (Ebara Manufacturing Co., Ltd., model “EPO-112”), and a dresser is used. Dressing was performed for 30 minutes under the conditions of a table rotation speed of 20 rpm, a dressing rotation speed of 19 rpm, and a dressing load of 5.1 kgf (made by Allied, trade name “# 325-63R”). Thereafter, chemical mechanical polishing was performed using the dressed chemical mechanical polishing pad under the following conditions to evaluate the polishing characteristics.
-Head rotation speed: 61 rpm
Head load: 3 psi (20.6 kPa)
・ Table rotation speed: 60rpm
・ Slurry supply speed: 300 cm ³ / min ・ Slurry: CMS8401 / CMS8452 (manufactured by JSR Corporation)

4.4.1. Evaluation of flatness A PETEOS film was sequentially laminated on a silicon substrate as a polishing object at 5,000 angstroms, and then a “SEMATECH 854” mask pattern was processed thereon. Then, a 250 angstrom tantalum nitride film and a 1,000 angstrom film were formed thereon. A test substrate in which a copper seed film and a 10,000 angstrom copper film were sequentially laminated was used.

  Under the conditions described in “4.4. Evaluation of Chemical Mechanical Polishing”, the object to be polished is subjected to chemical mechanical polishing for 1 minute, and the film thickness before and after the treatment is measured by an electroconductive film thickness measuring instrument (manufactured by KLA-Tencor Corporation). , Format “Omnimap RS75”), and the polishing rate was calculated from the film thickness before and after the treatment and the polishing treatment time. Then, the end point time at which the Cu is cleared is calculated as the time from the start of polishing to the end point detected by the change of the table torque current, and 1.2 times the end point detection time for the patterned wafer. After polishing, a precision step gauge (manufactured by KLA-Tencor Corporation) is used for a portion in which a pattern in which copper wiring portions having a width of 100 μm and insulating portions having a width of 100 μm are alternately continued in a direction perpendicular to the length direction is 3.0 mm. Dishing was evaluated by measuring the depression amount (hereinafter also referred to as “dishing amount”) of the copper wiring with a wiring width of 100 μm using the format “HRP-240”), and used as an index of flatness. The results are also shown in Table 1. The dishing amount is preferably less than 300 mm, more preferably less than 150 mm.

4.4.2. Evaluation of Scratches On the polished surface of the patterned wafer after polishing, the number of scratches on the entire surface of the wafer was measured using a wafer defect inspection apparatus (model “KLA2351” manufactured by KLA-Tencor Corporation). The number of scratches is preferably less than 30, more preferably less than 10.

4.5. Evaluation Results of Chemical Mechanical Polishing Pad According to the chemical mechanical polishing pads produced in Examples 1 to 5, since the relationship between D1 and D2 of the polishing layer is D1 <D2, all have 30 scratches. The dishing amount was less than 300 mm.

  On the other hand, according to the chemical mechanical polishing pad produced in Comparative Example 1 and Comparative Example 2, the relationship between D1 and D2 of the polishing layer is D1> D2, and thus the surface to be polished and the polishing dust are strong. The number of scratches increased by being pressed by pressure. The reason why the number of scratches in Comparative Example 2 is larger than the number of scratches in Comparative Example 1 is that the duro D hardness of the first layer in Comparative Example 2 is higher than the duro D hardness of the first layer in Comparative Example 1. This is thought to be caused by this.

  According to the chemical mechanical polishing pads produced in Comparative Examples 3 to 5, the relationship between D1 and D2 of the polishing layer is D1 = D2, so that the flatness of the surface to be polished in CMP and polishing defects ( It was impossible to achieve both reduction of scratches.

  That is, in Comparative Example 3, since the Duro D hardness of the first layer and the second layer is low in addition to the relationship of D1 = D2, the second layer cannot mitigate global deformation of the first layer. . Therefore, the flatness of the surface to be polished was significantly impaired.

  In Comparative Example 4, in addition to the relationship of D1 = D2, both the first layer and the second layer have high duro D hardness, so that the surface to be polished and the polishing debris are pressed with a strong pressure, resulting in a significant number of scratches. Increased.

  As is clear from the results of the above examples and comparative examples, the chemical mechanical polishing pad according to the present invention has a balance that can achieve both improvement in flatness of the surface to be polished in CMP and reduction in polishing defects (scratches). It turned out to be an excellent chemical mechanical polishing pad.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 10 ... Polishing layer, 11 ... Polishing surface, 12 ... 1st layer, 13 ... 2nd layer, 16 * 17 * 18 * 19 ... Recessed part, 20 ... Support layer, 30 ... Surface plate for polishing apparatus, 100 * 200 * 300 ... Chemical mechanical polishing pad

Claims (6)

A chemical mechanical polishing pad comprising a polishing layer formed from a plurality of layers,
The polishing layer includes a first layer having a polishing surface that comes into contact with an object to be polished when chemical mechanical polishing is performed, a second layer in contact with the first layer on a surface opposite to the polishing surface of the first layer, Having at least
The relationship between the Duro D hardness (D1) measured after immersing the first layer in water at 23 ° C. for 1 hour and the Duro D hardness (D2) measured without immersing the second layer in water is D1. <C2 is a chemical mechanical polishing pad.   The chemical mechanical polishing pad according to claim 1, wherein the value of D1 is 30D or more and 60D or less.   The chemical mechanical polishing pad according to claim 1 or 2, wherein the value of D2 is 50D or more and 85D or less.   The chemical mechanical polishing pad according to any one of claims 1 to 3, wherein a value (D1 / D2) of the D1 with respect to the value of the D2 is 0.5 or more and 0.9 or less.   The chemical mechanical polishing pad according to any one of claims 1 to 4, wherein the first layer includes water-soluble particles.   A chemical mechanical polishing method, wherein chemical mechanical polishing is performed using the chemical mechanical polishing pad according to any one of claims 1 to 5.

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