TWI428362B - Polishing pad and its manufacturing method (2) - Google Patents

Description

Polishing pad and its manufacturing method (2) Field of invention

The present invention relates to a polishing pad which is capable of stabilizing and high-polishing efficiency of optical materials such as lenses and mirrors, glass substrates for hard disks, glass substrates for hard disks, aluminum substrates, and general metal polishing processes. Flattening of materials with surface flatness. The polishing pad of the present invention can be suitably applied to, in particular, a germanium wafer and a device having an oxide layer, a metal layer or the like formed thereon for planarization before further layering or formation of the oxide layer or metal layer. The steps.

Background of the invention

A representative of a material requiring a high degree of surface flatness is a single crystal germanium disk called a germanium wafer for manufacturing a semiconductor integrated circuit (IC, LSI). In the manufacturing process of IC, LSI, etc., in order to form a reliable semiconductor junction for forming various thin films for circuit formation, it is required to perform high precision on the surface in each step of forming an oxide layer or a metal layer. Flat finishing. In this polishing finishing step, generally, the polishing pad is fixed on a rotatable supporting disk called a platform, and a workpiece such as a semiconductor wafer is fixed to the polishing head. Then, using the motion of both sides, a relative speed is generated between the platform and the polishing head, and the abrasive slurry containing the abrasive grains is continuously supplied on the polishing pad to perform the grinding operation.

The polishing property of the polishing pad is required to be excellent in planarity and in-plane uniformity of the polishing target, and the polishing rate is large. The flatness and in-plane uniformity of the object to be polished can be improved to a certain extent by allowing the polishing layer to have a high modulus of elasticity. Further, regarding the polishing rate, it is possible to form a foam containing bubbles to increase the amount of the slurry to be supported.

As a polishing pad satisfying the above characteristics, a polishing pad containing a synthetic resin-free foam or a polishing pad containing a polyurethane foam has been proposed (Patent Documents 1 and 2).

However, when the polishing pad including the foam is used, the contact area between the polishing target and the polishing pad is reduced, and the partial surface pressure is increased, so that scratches (scars) are likely to occur on the surface to be polished of the object to be polished. .

On the other hand, if a large number of semiconductor wafers are planarized by a polishing pad, the fine uneven portions on the surface of the polishing pad are abraded, and the performance of supplying the slurry to the processed surface of the semiconductor wafer is lowered, or the polishing speed is lowered. When lowered, the flattening characteristics deteriorate. Therefore, after the predetermined number of semiconductor wafers are planarized, it is necessary to update the surface of the polishing pad with a dresser and to roughen the surface (trimming). When the trimming is performed for a predetermined period of time, numerous fine uneven portions can be formed on the surface of the polishing pad, and the surface of the mat becomes a raised state.

A polishing pad comprising a conventional non-foaming body has a problem that the cutting speed at the time of dressing is low and the time spent on dressing is excessive.

Prior technical literature Patent literature

Patent Document 1: JP-A-2006-110665

Patent Document 2: Patent No. 4128606

An object of the present invention is to provide a polishing pad which is difficult to produce scratches on the surface of an object to be polished, and a method for producing the same, which improves the trimming property.

The inventors of the present invention have found that the above object can be attained by the following polishing mats in order to solve the above problems, and the present invention has been completed.

That is, the present invention relates to a polishing pad characterized in that it is a polishing pad having an abrasive layer containing a non-foamed polyurethane, and the aforementioned non-foamed polyurethane contains an isocyanate terminal prepolymer A, The reaction hardened product of the isocyanate terminal prepolymer B and the polyurethane raw material composition of the chain extender, wherein the isocyanate terminal prepolymer A is obtained by reacting the prepolymer A raw material composition to obtain a prepolymer A. The raw material composition contains a diisocyanate, a high molecular weight polyol (a), and a low molecular weight polyol, and the isocyanate terminal prepolymer B is obtained by reacting a prepolymer B raw material composition, and the prepolymer B raw material composition contains an isocyanate. The modified body and the high molecular weight polyol (b), the isocyanate reforming system, three or more diisocyanates are formed by addition polymerization; the isocyanate terminal prepolymer B is added in an amount relative to 100 parts by weight of the isocyanate terminal prepolymer. A is 5 to 30 parts by weight.

A feature of the invention is the formation of an abrasive layer from a non-foamed polyurethane. Thereby, the contact area between the object to be polished and the polishing layer is increased, and the surface pressure applied to the object to be polished is low and uniform, so that the occurrence of scratches on the surface to be polished can be effectively suppressed.

Further, the present inventors have found that the above-mentioned isocyanate terminal prepolymer A and the aforementioned isocyanate terminal prepolymer B are used as a raw material of the non-foamed polyurethane, and the reaction with the chain extender is used in the polymer. Introducing chemical cross-linking (regularly forming a three-dimensional cross-linked structure) will make the non-foamed polyurethane hard and brittle, and the cutting speed will increase when trimming, so the mat surface will be easily renewed. . Further, the chemical crosslinking network can be broadened by using the above two kinds of prepolymers. Thereby, the brittleness of the entire polishing layer can be made uniform, and variations in abrasion can be suppressed. Further, the isocyanate modified body of the three-dimensional cross-linking component is formed into a prepolymer, whereby the molecular weight of the polyurethane is easily adjusted. Thereby, the polyurethane is prevented from being excessively brittle, and it is possible to achieve a long life of the mat.

The high molecular weight polyol (a) is preferably a polyether polyol having a number average molecular weight of 500 to 5,000, and the diisocyanate is preferably toluene diisocyanate or dicyclohexylmethane diisocyanate. Further, the high molecular weight polyol (b) is preferably a polyether polyol having a number average molecular weight of from 250 to 2,000, and the isocyanate modified body is modified with a trimerized isocyanate type and/or a biuret type hexamethylene diisocyanate. Preferably, the isocyanate terminal prepolymer B is preferably synthesized by using an isocyanate index (NCO Index) of 3.5 to 6.0. By using these materials, the non-foaming polyurethane can be produced with good handleability, and the effect of the present invention is excellent.

The isocyanate terminal prepolymer B must be added in an amount of 5 to 30 parts by weight based on 100 parts by weight of the isocyanate terminal prepolymer A. When the amount of the isocyanate terminal prepolymer B added is less than 5 parts by weight, since the ratio of chemical crosslinking in the polymer is insufficient, the non-foamed polyurethane is difficult to be sufficiently brittle. On the other hand, when it exceeds 30 parts by weight, the ratio of chemical crosslinking in the polymer is excessive, and the hardness of the non-foamed polyurethane is too high, so that the surface of the object to be polished is likely to be scratched.

Further, the ASKER D hardness of the non-foamed polyurethane is preferably 65 to 80 degrees. When the Asker D hardness is less than 65 degrees, the flatness of the object to be polished tends to decrease. On the other hand, when it is more than 80 degrees, the flatness is good, but the in-plane uniformity of the object to be polished tends to decrease. In addition, scratches are likely to occur on the surface of the object to be polished.

Further, from the viewpoint of the balance between the renewability of the mat surface and the long life of the mat, the cutting speed of the polishing pad of the present invention is preferably more than 1 μm/min and 2 μm/min or less.

Further, the present invention relates to a method for producing a polishing pad comprising the steps of mixing and curing a first component and a second component to prepare a non-foamed polyurethane, wherein 100 parts by weight of the prepolymer is used. A raw material composition is reacted to obtain an isocyanate terminal prepolymer A, and the first component contains 5 to 30 parts by weight of an isocyanate terminal prepolymer B obtained by reacting a prepolymer B raw material composition to obtain The polymer A raw material composition contains a diisocyanate, a high molecular weight polyol (a), and a low molecular weight polyol, and the prepolymer B raw material composition contains an isocyanate modified body and a high molecular weight polyol (b), and an isocyanate reforming system The above diisocyanate is formed by addition polymerization, and the second component contains a chain extender.

Further, the present invention relates to a method of fabricating a semiconductor device comprising the step of polishing a surface of a semiconductor wafer using the polishing pad.

Simple illustration

Fig. 1 is a schematic block diagram showing an example of a polishing apparatus used for CMP polishing.

Fig. 2 is a schematic view showing a film thickness measurement position on the wafer at 73 o'clock.

Form for implementing the invention

The polishing pad of the present invention has an abrasive layer comprising a non-foamed polyurethane. The polishing pad of the present invention may be only the polishing layer described above, or may be a laminate of the polishing layer and other layers (for example, a buffer layer or the like).

The polyurethane resin is excellent in abrasion resistance, and a polymer having a desired physical property can be easily obtained by various changes in the composition of the raw material, and thus is particularly suitable as a material for forming the polishing layer.

The aforementioned non-foamed polyurethane is a reaction hardened product comprising a polyisocyanate raw material composition of an isocyanate terminal prepolymer A, an isocyanate terminal prepolymer B, and a chain extender, wherein the isocyanate terminal prepolymer A is a reaction product. The prepolymer A raw material composition is reacted to obtain a prepolymer A raw material composition comprising a diisocyanate, a high molecular weight polyol (a), and a low molecular weight polyol, and an isocyanate terminal prepolymer B is a prepolymer B. The raw material composition is reacted to obtain a prepolymer B raw material composition comprising an isocyanate modified body and a high molecular weight polyol (b), and an isocyanate reforming system in which three or more diisocyanates are subjected to addition polymerization.

As the diisocyanate, a compound known in the field of polyurethane can be used without particular limitation. For example, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-di An aromatic diisocyanate such as phenylmethane diisocyanate, 1,5-naphthalene diisocyanate, p-phenyl diisocyanate, m-phenyl diisocyanate, p-xylylene diisocyanate or m-xylylene diisocyanate, Aliphatic diisocyanate such as ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate or 1,6-hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, 4 An alicyclic diisocyanate such as 4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate or norbornane diisocyanate. One type of these types may be used, and two or more types may be used in combination. Among these, it is preferred to use toluene diisocyanate and dicyclohexylmethane diisocyanate in combination.

On the other hand, the isocyanate upgrading system in the present invention means a compound obtained by multimerization of three or more diisocyanates by addition polymerization or a mixture thereof. The isocyanate modified product may, for example, be 1) a trimethylolpropane addition type, 2) a biuret type, 3) a trimeric isocyanate type or the like, and particularly preferably a trimeric isocyanate type or a biuret type.

In the present invention, it is preferred to use an isocyanate modified diisocyanate to use an aliphatic diisocyanate, and particularly preferably 1,6-hexamethylene diisocyanate. Further, the isocyanate modified body may be a modified product such as a urethane reforming, a ureaform modification, or a biuret reforming.

The high molecular weight polyols (a) and (b) may be polyether polyols represented by polytetramethylene ether glycol, polyester polyols represented by polybutylene adipate, and polycaprolactone. a polyester polycarbonate polyol exemplified by a reaction product of a polyester diol such as a polyhydric alcohol or polycaprolactone and an alkylene carbonate, and reacting ethylene carbonate with a polyhydric alcohol, and then preparing the same A polyester polycarbonate polyol obtained by reacting a reaction mixture with an organic dicarboxylic acid, and a polycarbonate polyol obtained by transesterification of a polyhydroxy compound and an aryl carbonate. These may be used alone or in combination of two or more.

The number average molecular weight of the high molecular weight polyol (a) is not particularly limited, and is preferably from 500 to 5,000, more preferably from 1,000 to 2,000. When the number average molecular weight is less than 500, the hard segment is increased, and it tends to be a low toughness polyurethane. On the other hand, if the number average molecular weight exceeds 5,000, the polishing pad made of the polyurethane tends to have poor flattening characteristics because the polyurethane is too soft.

The number average molecular weight of the high molecular weight polyol (b) is not particularly limited and is preferably from 250 to 2,000, more preferably from 250 to 650. When the number average molecular weight is less than 250, the abrasion resistance is lowered, and it is prone to be difficult to extend the life of the mat. On the other hand, if the number average molecular weight exceeds 2,000, the renewability of the mat surface at the time of dressing tends to deteriorate.

A necessary raw material for the low molecular weight polyol isocyanate terminal prepolymer A. Examples of the low molecular weight polyol include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butanediol. 3-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol Alcohol, 1,4-bis(2-hydroxyethoxy)benzene, trimethylolpropane, glycerin, 1,2,6-hexanetriol, pentaerythritol, tetramethylolcyclohexane, methyl Glucosin, sorbitol, mannitol, dulcitol, sucrose, 2,2,6,6-tetrakis(hydroxymethyl)cyclohexanol, diethanolamine, N-methyldiethanolamine, and triethanolamine. These may be used alone or in combination of two or more. Further, a low molecular weight polyol can also be suitably used as a raw material of the isocyanate terminal prepolymer B.

Further, as the raw materials of the isocyanate terminal prepolymers A and B, a low molecular weight polyamine such as ethylenediamine, toluenediamine, diphenylmethanediamine or diethylenetriamine may be used in combination. Further, an alcoholamine such as monoethanolamine, 2-(2-aminoethylamino)ethanol or monopropanolamine may be used in combination. These may be used alone or in combination of two or more.

The mixing amount of the low molecular weight polyol and the low molecular weight polyamine is not particularly limited and is appropriately determined depending on the characteristics required for the polishing pad (abrasive layer) to be produced, except that the entire raw material component of the isocyanate terminal prepolymer A contains an active hydrogen group. 10 to 25% of the compound is preferred.

When the isocyanate terminal prepolymer B is produced, it is preferred to mix the isocyanate modified product and the high molecular weight polyol (b) so that the isocyanate index falls between 3.5 and 6.0, and preferably the isocyanate index is from 4.0 to 5.5.

The chain extender is an organic compound having at least two active hydrogen groups, and the active hydrogen group may, for example, be a hydroxyl group, a primary or secondary amino group, a thiol group (SH) or the like. Specifically, 4,4'-methylenebis(o-chloroaniline) (MOCA), 2,6-dichloro-p-phenylenediamine, 4,4'-methylene double (2,3- Dichloroaniline), 3,5-bis(methylthio)-2,4-toluenediamine, 3,5-bis(methylthio)-2,6-toluenediamine, 3,5-diethyl Toluene-2,4-diamine, 3,5-diethyltoluene-2,6-diamine, 1,3-propanediol bis(4-aminobenzoic acid) ester, poly-1,4-butanediol Bis(4-aminobenzoate), 4,4'-diamino-3,3',5,5'-tetraethyldiphenylmethane, 4,4'-diamino-3, 3'-diisopropyl-5,5'-dimethyldiphenylmethane, 4,4'-diamino-3,3',5,5'-tetraisopropyldiphenylmethane, 1 ,2-bis(2-aminophenylsulfanyl)ethane, 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, N, N '-Di-sec-butyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, m-xylylenediamine, N, Polyamines exemplified as N'-di-sec-butyl-p-phenylenediamine, m-phenylenediamine, and p-xylylenediamine, or the above-mentioned low molecular weight polyols and low molecular weight polyamines. One type of these types may be used, and two or more types may be used in combination.

The isocyanate terminal prepolymer B must be added in an amount of 5 to 30 parts by weight, preferably 5 to 20 parts by weight, per 100 parts by weight of the isocyanate terminal prepolymer A. Further, in order to obtain a polishing pad having desired polishing characteristics, the number of isocyanate groups of the isocyanate component of the active hydrogen group (hydroxyl group, amine group) of the chain extender is preferably 0.80 to 1.2, and further preferably 0.99 to 1.15. good. When the number of isocyanate groups is out of the above range, hardening failure occurs, the desired specific gravity and hardness are not obtained, and the polishing characteristics tend to be lowered.

In addition, the number average molecular weight of the isocyanate terminal prepolymers A and B is about 1,000 to 8,000, and it is excellent in workability, physical properties, and the like.

The non-foamed polyurethane can be produced by a known urethanation technique such as a melt method or a solution method, and it is preferably produced by a melt method in consideration of cost, operating environment, and the like. Further, a stabilizer such as an antioxidant, a lubricant, a pigment, a filler, an antistatic agent, and other additives may be added as needed.

Further, it is also possible to use a known catalyst for promoting a polyurethane reaction such as a tertiary amine system. The type and amount of the catalyst are selected after the mixing step, and the flow time of the mold of the specified shape is considered.

The production of the non-foamed polyurethane may be a batch method in which each component is metered into a container and stirred, or the components may be continuously supplied to a stirring device and stirred, and the polyurethane raw material may be sent out. The composition is a continuous production method for producing a molded article.

Further, the isocyanate terminal prepolymers A and B (the first component) are added to the reaction vessel, and then the chain extender (the second component) is introduced, and the mixture is stirred and poured into a mold of a predetermined size to prepare a cake. Alternatively, the method of slicing the block by a hand saw-like slicer may be formed into a sheet shape at the stage of the mold. Alternatively, it may be extruded from a T die to directly produce a sheet-like non-foamed polyurethane.

The ASKER D hardness of the non-foamed polyurethane is preferably from 65 to 80 degrees, more preferably from 70 to 75 degrees.

The polishing surface of the polishing pad (abrasive layer) of the present invention which is in contact with the object to be polished preferably has a concavo-convex structure for holding the ‧ renewed slurry. The polishing layer containing the non-foaming body lacks the effect of maintaining the slurry, but by forming the uneven structure on the polishing surface, the slurry can be efficiently maintained and renewed, and the adsorption to the object to be polished can be prevented. The damage caused by the grinding object. The uneven structure is not particularly limited as long as it retains the shape of the slurry, and examples thereof include an XY lattice groove, a concentric circular groove, a through hole, a non-through hole, a polygonal prism, a cylinder, a spiral groove, and an eccentric circular groove. Radial grooves and combinations of such grooves. Further, the uneven structure is generally regular, but the groove pitch, the groove width, the groove depth, and the like may be changed every certain range in order to obtain a desired slurry retention and renewal property.

The method for producing the uneven structure is not particularly limited, and examples thereof include a method of mechanically cutting using a jig such as a turning tool of a predetermined size, a method of pouring a resin into a mold having a predetermined surface shape, and hardening it. A method of producing a press-plate resin having a predetermined surface shape, a method of producing by a photolithography method, a method of producing by a printing technique, a method of producing laser light by using a carbon dioxide laser, or the like.

The thickness of the polishing layer is not particularly limited, and is usually about 0.8 to 4 mm, preferably 1.5 to 2.5 mm. The method for producing the polishing layer of the foregoing thickness may be a method of using a hand saw or a planer to make the block of the non-foamed polyurethane to a specified thickness, and pouring the resin into a mold having a specified thickness. A method of hardening the mold in the tank, a method using a coating technique or a sheet forming technique, and the like.

Further, the thickness deviation of the polishing layer is preferably 100 μm or less. When the thickness deviation exceeds 100 μm, there is a large surface wrinkle in the polishing layer, and a portion having a different contact state with respect to the polishing target is formed, which adversely affects the polishing property. In addition, in order to eliminate the thickness deviation of the polishing layer, the surface of the polishing layer is generally trimmed by a dresser for electrodepositing and fusing diamond abrasive grains at the initial stage of polishing, and if the above range is exceeded, the dressing time is prolonged. Production efficiency is reduced.

As a method of suppressing variations in the thickness of the polishing layer, a method of polishing the surface of the polishing sheet cut to a predetermined thickness can be mentioned. Further, in the case of polishing, it is preferred to carry out the stepwise step using abrasive materials having different particle sizes or the like.

The polishing pad of the present invention may be formed by laminating the polishing layer and the buffer layer.

The buffer layer compensates for the characteristics of the abrasive layer. In CMP, a buffer layer is necessary for both planarity and uniformity in which there is a trade-off relationship. The planarity refers to the flatness of the pattern portion when polishing an object to be polished having minute irregularities generated during pattern formation, and the uniformity refers to the uniformity of the entire object to be polished. The properties of the abrasive layer are used to improve planarity, and the characteristics of the buffer layer are utilized to improve uniformity. In the polishing pad of the present invention, the buffer layer is preferably used to be softer than the abrasive layer.

The buffer layer may, for example, be a fiber nonwoven fabric such as a polyester nonwoven fabric, a nylon nonwoven fabric or an acrylic nonwoven fabric, or a resin impregnated nonwoven fabric such as a polyurethane nonwoven fabric impregnated with polyurethane, a polyurethane foam, or a polyethylene foam. A rubber resin such as a polymer resin foam, a butadiene rubber or an isoprene rubber, or a photosensitive resin.

The means for bonding the polishing layer to the buffer layer may be, for example, a method in which the polishing layer and the buffer layer are sandwiched and pressed by a double-sided tape.

The double-faced tape has a general structure in which a bonding layer is provided on both sides of a substrate such as a nonwoven fabric or a film. When it is considered to prevent penetration of the slurry into the buffer layer, it is preferred to use a film as the substrate. Further, the composition of the adhesive layer may, for example, be a rubber-based adhesive or an acrylic adhesive. When the content of the metal ion is considered, the acrylic binder is suitable because the metal ion content is small. Further, since the composition of the polishing layer and the buffer layer may be different, the composition of each of the bonding layers of the double-sided tape may be made different so that the bonding strength of each layer is appropriate.

The polishing pad of the present invention may also be provided with a double-sided tape on the surface to which the platform is bonded. As the double-sided tape, a double-sided tape having a general structure in which a bonding layer is provided on both sides of the substrate can be used in the same manner as described above. The substrate may, for example, be a nonwoven fabric or a film. In view of the peeling of the polishing pad from the platform after use, it is preferred to use a film as the substrate. Further, the composition of the adhesive layer may, for example, be a rubber-based adhesive or an acrylic adhesive. When the content of the metal ion is considered, the acrylic binder is suitable because the metal ion content is small.

The semiconductor device is manufactured by the step of polishing the semiconductor wafer using the aforementioned polishing pad. A semiconductor wafer generally refers to a layer of wiring metal and an oxide film laminated on a germanium wafer. The polishing method and the polishing apparatus for the semiconductor wafer are not particularly limited. For example, as shown in Fig. 1, a polishing plate 2 having a polishing pad (polishing layer) 1 and a support table for supporting the semiconductor wafer 4 (polishing head) can be used. 5) a polishing device for supplying a support material for uniformly pressurizing the wafer, a supply mechanism for the abrasive 3, and the like. The polishing pad 1 is attached to the polishing platen 2 by, for example, being attached with a double-sided tape. The polishing platen 2 and the support table 5 are disposed such that the polishing pad 1 supported by the polishing pad 2 and the semiconductor wafer 4 are opposed to each other, and each of the rotating shafts 6 and 7 is provided. Further, a pressurizing mechanism for pressing the semiconductor wafer 4 to the polishing pad 1 is provided on the support table 5 side. At the time of polishing, the semiconductor wafer 4 is pressed onto the polishing pad 1 while the polishing platen 2 and the support table 5 are rotated, and the slurry is supplied while being polished. The flow rate of the slurry, the polishing load, the number of rotations of the polishing plate, and the number of rotations of the wafer are not particularly limited and can be appropriately adjusted.

Thereby, the portion where the surface of the semiconductor wafer 4 protrudes is removed, and is polished into a flat shape. Thereafter, the semiconductor device is fabricated by dicing, bonding, packaging, or the like. The semiconductor device is used for a calculation processing device, a memory, or the like.

Example

Hereinafter, the present invention will be described by way of examples, but the invention is not limited to the examples.

[Measurement, evaluation method] (quantitative average molecular weight)

The number average molecular weight is measured by GPC (gel permeation chromatography) and converted into standard polystyrene.

GPC device: manufactured by Shimadzu Corporation, LC-10A

Column: Made by Polymer Laboratories, (PLgel, 5μm, 500 ), (PLgel, 5μm, 100 ), and (PLgel, 5μm, 50 ) 3 column connections used

Flow rate: 1.0ml/min concentration: 1.0g/l

Injection volume: 40μl

Column temperature: 40 ° C

Dissolution: tetrahydrofuran

(measurement of specific gravity)

Follow JIS Z8807-1976. The prepared non-foamed polyurethane and polyurethane foam were cut into strips of 4 cm × 8.5 cm (thickness: arbitrary), and used as a sample for specific gravity measurement at a temperature of 23 ° C ± 2 Allow to stand for 16 hours in an environment of °C and humidity of 50% ± 5%. In the measurement, the specific gravity was measured using a hydrometer (manufactured by SARTORIUS).

(Measurement of hardness)

Follow JIS K6253-1997. The prepared non-foamed polyurethane and the polyurethane foam were cut into a size of 2 cm × 2 cm (thickness: arbitrary), and used as a sample for hardness measurement at a temperature of 23 ° C ± 2 ° C, Allow to stand for 16 hours in an environment with a humidity of 50% ± 5%. In the measurement, the samples were stacked to have a thickness of 6 mm or more. The hardness after 1 minute was measured by a durometer (manufactured by Kobunshi Co., Ltd., ASKER D type hardness meter).

(Measurement of surface roughness distribution)

The polishing pad thus produced was attached to a platform of a polishing apparatus (SPP600S, manufactured by Okamoto Machine Co., Ltd.). The surface of the polishing layer was trimmed under the conditions of a dressing pressure of 50 g/cm ² , a platform rotation number of 35 rpm, a flow rate of 200 ml/min, and a dressing time of 30 minutes using a dresser (manufactured by Asahi Diamond Co., Ltd.). After the trimming was completed, three samples (20 mm × 20 mm) were cut at intervals of 120° in the center position in the radial direction of the polishing pad. The surface roughness of each of the three samples was measured by a stylus type surface step difference measuring device (P-15 manufactured by KLA-Tencor Co., Ltd.), and the cubic root roughness Sq (μm) was calculated. Then, the average value (average Sq value) of the Sq values of the three samples was calculated. The average Sq value is preferably 6 to 9 μm. Further, the cubic root roughness Sq is obtained by the following equation when the average surface is the XY plane and the longitudinal direction is the Z axis, and the measured surface shape curve is z=f(x, y).

[Number 1]

(wherein Lx is the measured length in the x direction, and Ly is the measured length in the y direction.)

Measuring condition

Measurement area: 500 μm × 500 μm (measurement length 500 μm)

Scanning speed: scanning pitch 20μm/s

Broom: 51 (10 μm pitch)

Measuring load: 2mg

(Measurement of cutting speed)

The polishing pad thus produced was attached to a platform of a polishing apparatus (SPP600S, manufactured by Okamoto Machine Co., Ltd.). The surface of the polishing layer was trimmed under the conditions of trimming load of 9.71 bf, dressing pressure of 50 g/cm ² , platform rotation number of 35 rpm, flow rate of 200 ml/min, and dressing time of 30 minutes using a dresser (manufactured by Asahi Diamond Co., Ltd.). After the trimming was completed, a strip sample having a width of 20 mm and a length of 610 mm was cut out. The thickness was measured every 20 mm from the center of the sample (15 points on one side, 30 points in total). Then, the difference (abrasion amount) between the thicknesses of the unfinished center portions was calculated at each measurement position to calculate the average value. The cutting speed was calculated by the following formula. In the present invention, the cutting speed is preferably more than 1 μm/min and 2 μm/min or less, preferably 1.1 to 1.7 μm/min.

Cutting speed (μm/min) = average value of wear / (0.5 × 60)

(evaluation of scratches)

SPP600S (manufactured by Okamoto Machine Co., Ltd.) was used as a polishing device, and scratches were evaluated using the prepared polishing pad. A 8 μm ruthenium wafer was formed into a 1 μm thermal oxide film, and was polished under the following conditions, and then subjected to a surface defect detection device (Surfscan SP1 TBI) manufactured by KLA-Tencor Co., Ltd., and an edge exclusion amount (Edge Exclusion) of 5 mm was measured. The number of defects on the wafer from 0.19 to 2 μm. In the polishing conditions, a mash slurry (manufactured by SS12 Cabot Co., Ltd.) was added at a flow rate of 150 ml/min during polishing, and the polishing load was 350 g/cm ² , the number of polishing disk rotations was 35 rpm, and the number of wafer rotations was 30 rpm.

(Measurement of average grinding speed)

SPP600S (manufactured by Okamoto Machine Co., Ltd.) was used as a polishing apparatus, and the average polishing rate was evaluated using the polishing pad produced. A 8 μm ruthenium wafer was formed into a 1 μm thermal oxide film, and after polishing for 1 minute under the following conditions, the measured value of the film pressure after polishing at a predetermined position on the wafer at 73 points was calculated as shown in FIG. 2 . Average grinding speed. In the measurement of the film thickness of the oxide film, an interference type film thickness measuring device (manufactured by Otsuka Electronics Co., Ltd.) was used. In the polishing conditions, a mash slurry (manufactured by SS12 Cabot Co., Ltd.) was added at a flow rate of 150 ml/min during polishing, and the polishing load was 350 g/cm ² , the number of polishing disk rotations was 35 rpm, and the number of wafer rotations was 30 rpm.

Example 1

1229 parts by weight of toluene diisocyanate (2,4-toluene diisocyanate/2,6-toluene diisocyanate=80/20 mixture) and 272 parts by weight of 4,4'-dicyclohexylmethane diisocyanate were added to the vessel. 1901 parts by weight of polytetramethylene glycol diol having a number average molecular weight of 1018 and 198 parts by weight of diethylene glycol were reacted at 70 ° C for 4 hours to obtain an isocyanate terminal prepolymer A.

Further, 100 parts by weight of a polymerized 1,6-hexamethylene diisocyanate (manufactured by Bayer Ammonium Co., Ltd., Sumidur N-3300, a trimeric isocyanate type) as an isocyanate modified body was added to the vessel. 16.3 parts by weight of a polytetramethylene glycol having an average molecular weight of 250 (isocyanate index: 4.0) was reacted at 100 ° C for 3 hours to obtain an isocyanate terminal prepolymer B (1).

100 parts by weight of the aforementioned prepolymer A and 16 parts by weight of the aforementioned prepolymer B (1) were mixed and defoamed by a planetary stirring and defoaming device. Thereafter, 33.1 weight of molten 4,4'-methylenebis(o-chloroaniline) at 120 ° C was added to the mixed solution, mixed with a planetary stirring defoaming device and defoamed to prepare a polyurethane. Raw material composition. The composition was poured into an open mold (molded container) having a length of 800 mm and a depth of 2.5 mm, and cured at 100 ° C for 16 hours to obtain a non-foamed polyurethane sheet. Next, the sheet was subjected to surface polishing treatment using a polishing machine (manufactured by AMITEC Co., Ltd.) to a thickness of 1.27 mm to form a sheet having a uniform thickness. The polished sheet is punched at a diameter of 61 cm, using a groove processing machine ( (Technical Co., Ltd.), a groove having a groove width of 0.25 mm, a groove pitch of 1.50 mm, and a groove depth of 0.40 mm was processed on the surface to obtain a polishing layer. A double-faced tape (manufactured by Sekisui Chemical Co., Ltd., double-sided bonding tape) was bonded to the surface of the polishing layer opposite to the groove processing surface by a laminator. Further, the surface of the corona-treated buffer layer (manufactured by Toray Industries, polyethylene foam, TORAY PEF, thickness: 0.8 mm) was subjected to a buffing treatment, and was bonded to the above-mentioned double-faced tape using a laminator. Further, a double-sided tape was attached to the other side of the buffer layer using a laminator to form a polishing pad.

Example 2

Except in Example 1, the addition amount of the prepolymer B (1) was changed from 16 parts by weight to 8 parts by weight, and the amount of 4,4'-methylene bis(o-chloroaniline) added was from 33.1 by weight. A polishing pad was produced in the same manner as in Example 1 except that the amount was changed to 29.8 parts by weight.

Example 3

100 parts by weight of polyistained 1,6-hexamethylene diisocyanate (manufactured by Bayer Ammonium Co., Sumidur N-3300, trimeric isocyanate type) and 42.4 weights as isocyanate modified bodies were added to the vessel. A polytetramethylene glycol (isocyanate index: 4.0) having a number average molecular weight of 650 was reacted at 100 ° C for 3 hours to obtain an isocyanate terminal prepolymer B (2).

Except in Example 1, 16 parts by weight of prepolymer B (2) was used instead of 16 parts by weight of prepolymer B (1), and the amount of 4,4'-methylenebis(o-chloroaniline) was added from A polishing pad was produced in the same manner as in Example 1 except that the weight of 33.1 was changed to 31.9 parts by weight.

Example 4

100 parts by weight of multimerized 1,6-hexamethylene diisocyanate (manufactured by Bayer Ammonium Co., Ltd., Sumidur N-3300, trimeric isocyanate type) as an isocyanate modified product, and 39.1 by weight were added to the vessel. A polyethylene glycol (isocyanate index: 4.0) having a number average molecular weight of 600 was reacted at 100 ° C for 3 hours to obtain an isocyanate terminal prepolymer B (3).

In addition to in Example 1, 16 parts by weight of prepolymer B (3) was used instead of 16 parts by weight of prepolymer B (1), and the amount of 4,4'-methylene bis(o-chloroaniline) was added from A polishing pad was produced in the same manner as in Example 1 except that the weight of 33.1 was changed to 32.0 parts by weight.

Comparative example 1

Except that in Example 1, the prepolymer B (1) was not added, and the addition amount of 4,4'-methylene bis(o-chloroaniline) was changed from 33.1 wt. to 26.6 wt. 1 The same method was used to make a polishing pad.

Comparative example 2

Except in Example 1, the addition amount of the prepolymer B (1) was changed from 16 parts by weight to 35 parts by weight, and the amount of 4,4'-methylene bis(o-chloroaniline) was changed from 33.1 by weight. A polishing pad was produced in the same manner as in Example 1 except that the amount was changed to 38.5 parts by weight.

Comparative example 3

100 parts by weight of the aforementioned prepolymer A, 23.3 parts by weight of prepolymer B (1), and 3.7 parts by weight of a lanthanoid surfactant (manufactured by Toray Dow Corningone, SH-192) were placed in a polymerization vessel and allowed to be Mix, adjust to 80 ° C and defoam under reduced pressure. Thereafter, vigorous stirring was carried out for about 4 minutes at a rotation number of 900 rpm using a stirring blade to allow bubbles to enter the reaction system. 36.1 parts by weight of 4,4'-methylenebis(o-chloroaniline) previously melted at 120 ° C was added thereto. The mixture was stirred for about 70 seconds and then poured into a pan-type open mold (molding container). The mixture was placed in an oven at the time when the mixture had no fluidity, and post-cured at 100 ° C for 16 hours to obtain a polyurethane foam cake. The aforementioned polyurethane foam block heated to about 80 ° C was sliced using a microtome (manufactured by AMITEC Co., Ltd., VGW-125) to obtain a polyurethane sheet. Next, the sheet was subjected to surface polishing treatment using a polishing machine (manufactured by AMITEC Co., Ltd.) to a thickness of 1.27 mm to form a sheet having a uniform thickness. The polished sheet is punched at a diameter of 61 cm, using a groove processing machine ( (Technical Co., Ltd.) processed a concentric groove having a groove width of 0.25 mm, a groove pitch of 1.50 mm, and a groove depth of 0.40 mm to obtain a polishing layer. Thereafter, a polishing pad was produced in the same manner as in Example 1.

1. . . Abrasive pad (abrasive layer)

2. . . Grinding plate

3. . . Abrasive (slurry)

4. . . Grinding object (semiconductor wafer)

5. . . Support table (grinding head)

6, 7. . . Rotary axis

Fig. 1 is a schematic block diagram showing an example of a polishing apparatus used for CMP polishing.

Fig. 2 is a schematic view showing a film thickness measurement position on the wafer at 73 o'clock.

1. . . Abrasive pad (abrasive layer)

2. . . Grinding plate

3. . . Abrasive (slurry)

4. . . Grinding object (semiconductor wafer)

5. . . Support table (grinding head)

6, 7. . . Rotary axis

Claims (7)

A polishing pad comprising a polishing layer composed of a non-foamed polyurethane, characterized by a reaction hardened material of the non-foamed polyurethane-polyurethane raw material composition, and The polyurethane raw material composition contains: an isocyanate terminal prepolymer A which is obtained by reacting a prepolymer A raw material composition containing a diisocyanate, a high molecular weight polyol (a), and a low molecular weight polyol. Isocyanate terminal prepolymer B obtained by reacting a prepolymer B raw material composition containing an isocyanate modified body and a high molecular weight polyol (b), and the isocyanate upgrading system is added by And a chain extender; and the isocyanate terminal prepolymer B is added in an amount of 5 to 30 parts by weight based on 100 parts by weight of the isocyanate terminal prepolymer A. A polishing pad according to claim 1, wherein the high molecular weight polyol (a) has a polyether polyol having an average molecular weight of 500 to 5,000, and a diisocyanate toluene diisocyanate and dicyclohexylmethane diisocyanate. A polishing pad according to claim 1 or 2, wherein the high molecular weight polyol (b) has a polyether polyol having an average molecular weight of 250 to 2000, an isocyanate reforming system, a trimeric isocyanate type and/or a biuret type. The hexamethylene diisocyanate modified body and the isocyanate terminal prepolymer B are synthesized by an isocyanate index (NCO Index) of 3.5 to 6.0. For example, in the polishing pad of claim 1, wherein the ASKER D hardness of the non-foamed polyurethane is 65 to 80 degrees. The polishing pad of claim 1, wherein the cutting speed is greater than 1 μm/min and less than 2 μm/min. A method for producing a polishing pad comprising the steps of: mixing and curing a first component and a second component containing a chain extender to produce a non-foamed polyurethane; wherein the first component is relative to 100 weight The isocyanate terminal prepolymer A contains 5 to 30 parts by weight of the isocyanate terminal prepolymer B; and the isocyanate terminal prepolymer A is a prepolymer containing a diisocyanate, a high molecular weight polyol (a) and a low molecular weight polyol. The polymer A raw material composition is reacted and produced, and the isocyanate terminal prepolymer B is obtained by reacting a prepolymer B raw material composition containing an isocyanate modified body and a high molecular weight polyol (b). Further, the isocyanate reforming system is polymerized by addition of three or more diisocyanates. A method of fabricating a semiconductor device comprising the steps of: polishing a surface of a semiconductor wafer using a polishing pad as in claim 1 of the patent application.