JP3494641B1 - Polishing pad for polishing semiconductor wafers - Google Patents

Abstract

Kind Code: A1 A polishing method that maintains a high polishing rate, has a low resistance when a wafer is separated from a polishing pad after polishing is completed, does not cause a dechucking error, and therefore does not cause damage to the wafer and decrease in work efficiency. Providing a polishing layer for a pad or polishing pad. A polishing pad having a polishing layer made of a polyurethane resin foam, wherein a dynamic friction coefficient of a surface of the polishing layer is 0.1 to 0.7.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a silicon wafer as well as a silicon wafer.
And devices on which oxide layers, metal layers, etc. are formed
Highly planarized before further stacking / forming these layers
The present invention relates to a polishing pad for polishing a semiconductor wafer (hereinafter, also simply referred to as “polishing pad”) used in the step of performing .

[0002]

2. Description of the Related Art A semiconductor integrated circuit (IC, LSI) is a typical material that requires a high degree of surface flatness.
There is a single crystal silicon disk called a silicon wafer used for manufacturing. In order to form a reliable semiconductor junction of various thin films used for circuit production in the manufacturing process of ICs, LSIs, etc., a silicon wafer is required to have a highly accurate flat surface finish in each thin film manufacturing process.

In recent years, miniaturization of wiring and multi-layer wiring have been required for the purpose of increasing the density of semiconductor devices, and it has been required to increase the resolution in pattern formation. In order to increase the resolution, it is necessary to use light with a shorter wavelength or use an optical system with a larger numerical aperture NA.
The larger the, the shallower the depth of focus. On the other hand, the surface of the silicon wafer has the contradictory problem that the unevenness is amplified as the processing progresses in the device fabrication process, and accurate patterning cannot be performed. In order to solve these contradictory problems, extremely high precision planarization technology is required, and chemical mechanical polishing (CMP: Chemical) is required.
The Mechanical Polishing method has been used as a powerful tool.

A chemical mechanical polishing apparatus (CMP apparatus) for flattening a processed surface by the CMP method will be described with reference to FIG. The CMP apparatus used in the CMP method includes a polishing surface plate 2 that supports a polishing pad 1 and a support base (polishing head) 4 that supports a material to be polished (wafer) 3. The polishing surface plate 2 and the support base 4 are arranged so that the polishing pad 1 and the material to be polished 3 which are respectively supported face each other, and are configured to be rotatable about rotation shafts 6 and 7. The material 3 to be polished is attached to the support 4, and a pressure mechanism for pressing the material 3 to be polished against the polishing pad 1 is provided at the time of polishing. The polishing agent supply mechanism 5 polishes a polishing solution in which polishing agent particles such as silica particles are dispersed in an alkaline solution to a polishing platen 2.
It is supplied on the upper polishing pad 1.

A polyurethane foam sheet having a porosity of about 30 to 35% is generally used as the polishing pad used for the above-mentioned highly accurate polishing. Further, in the polishing pad, it is important that the polishing is completed in the shortest possible time. Therefore, the polishing pad is required to have a high polishing rate.

For example, a method for producing a microcellular polyurethane foam having uniform microfoaming without using a different substance such as a foaming agent or a micro hollow foam, and a polishing sheet obtained by the method are disclosed. Patent Document 1).

Further, for the purpose of favorably suppressing the thinning phenomenon in the formation of groove wiring or damascene wiring, a porous sheet having a sintered body of ultra-high molecular weight polyethylene powder and having a dry dynamic friction coefficient of 0.3 or less is used. The following semiconductor wafer polishing pad is disclosed (Patent Document 2).

[0008]

[Patent Document 1] Japanese Patent Laid-Open No. 2000-178374

[Patent Document 2] Japanese Patent Laid-Open No. 2001-176829

However, when the conventional polyurethane foam sheet is used as the polishing pad or the polishing layer of the polishing pad, the polishing efficiency is improved by increasing the polishing rate, but the wafer is polished after the polishing is completed. There is a problem in that the resistance when the pad is released increases, a so-called dechuck error occurs, the wafer is damaged, and the work efficiency decreases. Further, with the polyurethane foam described in Patent Document 1, it is difficult to prevent a dechuck error while maintaining a high polishing rate. Patent Document 2
The semiconductor wafer polishing pad described above cannot maintain a high polishing rate because it is made of a sintered body of ultra-high molecular weight polyethylene powder. Furthermore, although it is a requirement that the porous sheet has a dry dynamic friction coefficient of 0.3 or less, the measuring method thereof is not described at all, and it is completely unknown what functions and characteristics it has.

An object of the present invention is to maintain a high polishing rate, yet to reduce the resistance when the wafer is separated from the polishing pad after the completion of polishing, to prevent the occurrence of dechucking errors, and therefore to prevent the damage of the wafer and the deterioration of the working efficiency. It is to provide a polishing pad or a polishing layer of a polishing pad that does not occur.

The polishing pad of the present invention has a polishing layer made of a polyurethane resin foam, and the surface roughness of the polishing layer is 3 to.
10 μm, the average bubble diameter of the polishing layer is 20 to 90 μm
And the coefficient of kinetic friction of the surface of the polishing layer is 0.1 to 0.7.

The coefficient of dynamic friction on the surface of the polishing layer is 0.1 to 0.7.
By using the polishing pad that is, the polishing rate is maintained high, and the resistance when the wafer is separated from the polishing pad after polishing is small, and dechuck error does not occur.
Therefore, it is possible to obtain a polishing pad that does not damage the wafer or reduce the work efficiency.

When the coefficient of dynamic friction on the surface of the polishing layer is less than 0.1, the resistance to the object to be polished becomes small and the interaction between the polishing pad and the object to be polished becomes small, so that the polishing rate becomes low and the polishing efficiency becomes low. Is reduced. If the dynamic friction coefficient of the surface of the polishing layer is larger than 0.7, the resistance between the polishing pad and the object to be polished increases during polishing, and as a result, the object to be polished comes off the holder, so-called dechuck error occurs. The coefficient of dynamic friction on the surface of the polishing layer is more preferably 0.2 to 0.6.

The dynamic friction coefficient of the surface of the polishing layer is the temperature (23 ±
2) Pyrex (registered trademark) (manufactured by Corning Incorporated), which is a highly heat-resistant glass in an environment of ℃ and humidity (50 ± 6)% RH
Contacting with, and at a pressure of 10.8 kPa, a speed of 20 cm /
It is a value measured by moving at min.

In the present invention, the polyurethane resin foam is preferably of the closed cell type.

Since the polyurethane resin has flexibility in addition to the necessary hardness, minute scratches on the object to be polished,
That is, scratches are reduced. Further, the contact area between the polishing layer and the object to be polished becomes smaller due to the bubbles on the surface, and a polishing pad having a dynamic friction coefficient within the above range can be relatively easily manufactured.

The closed cell type polyurethane resin foam does not have to be 100% completely composed of only closed cells, and continuous cells may be partially present. The closed cell rate may be 90% or more.

[0017] The polishing pad of the present invention, the surface roughness of the polishing layer is 3 to 10 [mu] m, preferably 4～7Myuemu.
If the surface roughness is less than 3 μm, the surface area of the polishing layer that effectively acts on polishing increases, and as a result, the coefficient of dynamic friction increases and so-called dechuck error may occur. On the other hand, when the surface roughness is larger than 10 μm, the surface area of the polishing layer that effectively acts on the polishing is small, and as a result, the dynamic friction coefficient is small and the polishing efficiency is lowered. By setting the surface roughness within the range of 3 to 10 μm, the dynamic friction coefficient of the polishing layer surface can be controlled relatively easily within the target range.

In the polishing pad of the present invention , the average cell diameter of the polishing layer is 20 to 90 μm, preferably 20 to 6 μm.
It is 0 μm. Generally, when the foaming rate is constant, the smaller the average bubble diameter, the smaller the polishing effective area of the polishing layer (contact area with the object to be polished), and the larger the average bubble diameter, the larger the polishing effective area. Become. Average bubble diameter is 2
If it is less than 0 μm, the effective polishing area decreases, and as a result, the coefficient of dynamic friction becomes too small and the polishing rate tends to decrease. On the other hand, when the average bubble diameter is larger than 90 μm, the gap between the bubbles becomes large and the effective polishing area also becomes large. As a result, the coefficient of dynamic friction becomes too large, which may cause a wafer dechucking error. By setting the average bubble diameter of the polishing layer to 20 to 90 μm, a polishing pad having excellent polishing characteristics can be obtained,
Moreover, the coefficient of dynamic friction on the surface of the polishing layer can be controlled within a target range relatively easily.

The polyurethane resin foam is 0.05
It is preferable to contain ˜5 wt% of a silicone-based surfactant. The content of silicone surfactant is 0.
By setting the amount within the range of 05 to 5 wt%, the average bubble diameter of the polishing layer can be controlled within the above range.

The polishing pad (polishing layer) is preferably a closed cell type polyurethane resin foam, and is stable closed cell type polyurethane resin foam when the amount of the silicone surfactant is less than 0.05 wt%. Is difficult to obtain. Further, since the hardness of the polyurethane resin is increased and the surface of the polishing pad is substantially hardened, the surface area that effectively acts on polishing is reduced and the dynamic friction coefficient tends to be reduced. On the other hand, when it is more than 5 wt%, the strength of the polishing pad is lowered by adding the surfactant, and the flattening property tends to be deteriorated in polishing. Further, since the surface of the polishing pad is substantially softened, the surface area that effectively acts on the polishing is increased, and the dynamic friction coefficient tends to be increased.

As a method of controlling the dynamic friction coefficient, it is possible to carry out a method such as changing the surface shape of the polishing layer or adding an additive. Examples of methods for changing the surface shape of the polishing layer include controlling the groove shape on the pad surface and changing the surface roughness of the pad surface by dressing with a diamond dresser or the like. Furthermore, in the formulation in which the additive is added, by changing the amount of the surfactant added or the content of the surfactant, in the case of the above-mentioned bubble-containing polishing pad, the formation state of bubbles can be changed and the dynamic friction coefficient can be changed. It is possible.

The present invention is also a method for producing a polishing pad from a polyurethane resin foam, which comprises slicing a block of polyurethane resin foam into a sheet to produce a polyurethane resin foam sheet, and Semiconductor comprising a step of dressing at least a polishing surface side of a polyurethane resin foam sheet
The present invention relates to a method for manufacturing a polishing pad for polishing a wafer .

Furthermore, the present invention relates to a method for manufacturing a semiconductor device, which comprises a step of polishing the surface of a semiconductor wafer using the polishing pad described above.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION In the polishing pad of the present invention,
Surface roughness of polishing layer is 3 to 10 μm, average bubble diameter of polishing layer
Is 20 to 90 μm, and the coefficient of dynamic friction of the surface of the polishing layer is 0.1 to 0.7 (which may have grooves on the surface of the polishing layer), and from a polyurethane resin foam There is no particular limitation as long as it is a polishing layer.
As the polyurethane resin foam, it is preferable to use a foamed polymer obtained by reacting and curing an isocyanate-terminated urethane prepolymer and an organic diamine compound as a chain extender in a foamed state.

The isocyanate-terminated urethane prepolymer is obtained by reacting a polyisocyanate with a polyol compound known in the technical field of polyurethane in excess of isocyanate groups.

As the polyisocyanate, for example, 2,4- and / or 2,6-diisocyanate toluene, 2,2'-, 2,4'- and / or 4,4'-diisocyanate diphenylmethane, 1,5- Naphthalene diisocyanate, p- and m-phenylene diisocyanate, dimeryl diisocyanate, xylylene diisocyanate, diphenyl-4,4'-diisocyanate, 1,3- and 1,4-tetramethylxylidene diisocyanate, tetramethylene diisocyanate, 1,
6-hexamethylene diisocyanate, dodecamethylene diisocyanate, cyclohexane-1,3- and 1,
4-diisocyanate, 1-isocyanate-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (= isophorone diisocyanate), bis- (4-
Isocyanate cyclohexyl) methane (= hydrogenated MD
I), 2- and 4-isocyanatocyclohexyl-2
′ -Isocyanate cyclohexylmethane, 1,3- and 1,4-bis- (isocyanatemethyl) -cyclohexane, bis- (4-isocyanate-3-methylcyclohexyl) methane and the like can be mentioned.

Examples of the polyol compound include compounds known as polyol compounds in the technical field of polyurethane such as hydroxy-terminated polyester, polycarbonate, polyester carbonate, polyether, polyether carbonate and polyester amide. Of these, polyethers and polycarbonates having good hydrolysis resistance are preferable, and polyethers are particularly preferable from the viewpoint of price and melt viscosity.

As the polyether polyol, a starting compound having a reactive hydrogen atom, for example, ethylene oxide,
Mention may be made of reaction products with at least one alkylene oxide such as propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin. Examples of the starting compound having a reactive hydrogen atom include water, bisphenol A, and the dihydric alcohols described below used in the production of polyester polyol.

Examples of the polycarbonate polyol having a hydroxy group include 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol,
Mention may be made of reaction products of diols such as polypropylene glycol and / or polytetramethylene glycol with phosgene, diallyl carbonate (eg diphenyl carbonate) or cyclic carbonates (eg propylene carbonate).

As the polyester polyol, a reaction product of a dihydric alcohol and a dibasic carboxylic acid can be mentioned, but in order to improve hydrolysis resistance, it is preferable that the distance between ester bonds is long, and both are long. A combination of chain components is desirable.

The dihydric alcohol constituting the polyester polyol is not particularly limited,
For example ethylene glycol, 1,3- and 1,2-propylene glycol, 1,4- and 1,3- and 2,3-
Butylene glycol, 1,6-hexanediol, 1,
8-octanediol, neopentyl glycol, cyclohexanedimethanol, 1,4-bis- (hydroxymethyl) -cyclohexane, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2, 2,4-trimethyl-1,3-pentanediol, diethylene glycol, dipropylene glycol,
Triethylene glycol, tripropylene glycol,
Examples thereof include dibutylene glycol.

The dibasic carboxylic acid constituting the polyester polyol includes aliphatic, alicyclic, aromatic and / or
Alternatively, a heterocyclic dibasic carboxylic acid can be used without particular limitation, but an aliphatic or alicyclic dibasic carboxylic acid is required because the terminal NCO prepolymer to be produced has a liquid or low melt viscosity. Is preferably used, and when an aromatic system is applied, it is preferably used in combination with an aliphatic or alicyclic carboxylic acid.

Examples of the above-mentioned suitable dibasic carboxylic acid include succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, o-cyclohexanedicarboxylic acid, m-cyclohexanedicarboxylic acid, p-
Cyclohexanedicarboxylic acid, dimer-fatty acid, oleic acid and the like can be mentioned.

As the polyester polyol, a ring-opening polymer of a lactone such as ε-caprolactone or a polyester which is a condensation polymer of a hydroxycarboxylic acid such as ε-hydroxycaproic acid can also be used.

In the above isocyanate-terminated urethane prepolymer, a low molecular weight polyol may be used in addition to the polyol compound. Examples of the low molecular weight polyol include dihydric alcohols used for producing the polyester polyol described above, but include diethylene glycol, 1,3-butylene glycol and 3-methyl-glycol.
It is preferable to use any one of 1,5-pentanediol and 1,6-hexamethylene glycol, or a mixture thereof. Use of a dihydric alcohol having a longer chain than 1,6-hexamethylene glycol gives an appropriate one in terms of reactivity during cast molding and hardness of the finally obtained polyurethane abrasive molded article. May be

The isocyanate component is appropriately selected according to the pot life required at the time of cast molding, and
Since the resulting terminal NCO prepolymer needs to have a low melt viscosity, it is applied alone or as a mixture of two or more kinds.

As the organic diamine compound used as the chain extender for the isocyanate-terminated prepolymer in the present invention, known chain extenders can be used without particular limitation. For example, 3,3'-dichloro-4, 4'-diaminodiphenylmethane, chloroaniline-modified dichlorodiaminodiphenylmethane, 1,2-bis (2-aminophenylthio) ethane, trimethylene glycol-di-p-
Aminobenzoate, 3,5-bis (methylthio)-
2,6-toluenediamine, 1,3-diethyl-5-methyl-diaminobenzene, 1,3,5-triethyl-
2,4-diaminobenzene, 1,5-diethyl-3-methyl-2,4-diaminobenzene, 4,4′-methylenedianiline in which the o-position of the amino group is substituted with a methyl group, an ethyl group or the like Etc.

As a method for producing a polyurethane resin foam using the above-mentioned isocyanate-terminated prepolymer,
Examples thereof include, but are not limited to, a method of adding hollow beads (for example, Expancel manufactured by Nippon Philite Co., Microsphere manufactured by Matsumoto Yushi Co., Ltd.) and a method of forming a foam by a mechanical foaming method. Both may be used in combination, but a mechanical foaming method using a silicone-based surfactant which is a copolymer of polyalkylsiloxane and polyether and has no active hydrogen group is more preferable. As such a silicone-based surfactant, SH-192 (manufactured by Toray Dow Corning Silicone) or the like is exemplified as a suitable compound.

As an example of a method for producing a polyurethane resin foam constituting the polishing layer of the polishing pad of the present invention, a method using an isocyanate-terminated prepolymer will be described. The method for producing such a polyurethane closed-cell foam,
It has the following steps.

(1) Stirring Step for Preparing a Dispersion of Isocyanate-Terminated Prepolymer A silicone surfactant is added to the isocyanate-terminated prepolymer and stirred with a non-reactive gas to disperse the non-reactive gas as fine bubbles. To obtain an air bubble dispersion liquid. When the prepolymer is solid at room temperature, it is preheated to an appropriate temperature and melted before use. (2) Mixing Step of Hardener (Chain Extender) The chain extender is added to the above bubble dispersion liquid, and the mixture is stirred. (3) Curing Step An isocyanate-terminated prepolymer mixed with a chain extender is poured into a predetermined mold and cured by heating.

A block made of the polyurethane resin foam produced as described above is sliced into a predetermined size to obtain a polyurethane resin foam sheet.

In addition to this method, the polyurethane resin foam sheet may be prepared by pouring the polyurethane component into a mold having a cavity having the same thickness as the intended polishing layer.

The polishing layer has a thickness of about 0.8 mm to 2 mm, and a sheet having a thickness of about 1.2 mm is usually used.

In the present invention, at least the polishing surface side (the surface side in contact with the object to be polished) of the polyurethane resin foam sheet may be dressed with a diamond dresser or the like so that the surface roughness becomes 3 to 10 μm. preferable. The surface roughness can be adjusted within a target range by appropriately selecting a dressing material (for example, sandpaper, diamond dresser).

On the surface of the polishing layer which comes into contact with the object to be polished,
It is preferable to have a surface shape that holds and updates the slurry. By using a fine foam of polyurethane resin, it has many openings in the polishing surface and has a function of holding the slurry, but in order to perform further slurry holding and slurry renewal efficiently, Further, in order to prevent the object to be polished from being broken due to adsorption to the object to be polished, it is preferable that the surface of the polishing layer has surface irregularities. It is not particularly limited as long as it has a surface shape that holds and renews the slurry. For example, XY lattice grooves, concentric circular grooves, through holes,
Examples include holes that do not penetrate, spiral grooves, eccentric circular grooves, radial grooves, and combinations of these grooves. The groove area in the polishing layer surface is not particularly limited,
Generally, it is 20 to 25%. When a groove is formed on the surface of the polishing layer, the dynamic friction coefficient tends to be small. However, in the present invention, the coefficient of dynamic friction on the surface of the polishing layer is 0.1 to 0. It must be within the range of 7.

The method for producing the surface shape is not particularly limited, but for example, a method of mechanically cutting using a jig such as a cutting tool of a predetermined size, or a resin having a predetermined surface shape is poured with a resin. A method of making by denting and hardening, a method of making a resin by pressing with a press plate having a predetermined surface shape, a method of making by using photolithography, a method of making by using a printing method, a carbon dioxide laser, etc. And a method of manufacturing with a laser beam.

As the non-reactive gas used for forming the fine bubbles, those which are not combustible are preferable, and specifically, nitrogen, oxygen, carbon dioxide gas, a rare gas such as helium and argon, or a mixed gas thereof is preferable. Is used, and it is most preferable in terms of cost to use dry air to remove moisture.

A known stirring device can be used without particular limitation as a stirring device for dispersing the non-reactive gas into fine bubbles to disperse it in the isocyanate-terminated prepolymer containing a silicone-based surfactant. Examples thereof include a homogenizer, a dissolver, and a two-axis planetary mixer (planetary mixer). The shape of the stirring blade of the stirring device is not particularly limited, but use of a whipper type stirring blade is preferable because fine bubbles can be obtained.

It is a preferred embodiment that different stirring devices are used for stirring for preparing the air bubble dispersion in the stirring step and stirring for adding and mixing the chain extender in the mixing step. In particular, the stirring in the mixing step may not be the stirring for forming bubbles, and it is preferable to use a stirring device that does not involve large bubbles. As such a stirring device,
A planetary mixer is preferred. Even if the same stirring device is used as the stirring device in the stirring process and the mixing process, there is no problem, and it is also preferable to adjust the stirring conditions such as adjusting the rotation speed of the stirring blades as needed before use. .

In the method for producing a polyurethane foam of the present invention, heating and post-curing the foam reacted by pouring the cell dispersion into a mold until the foam does not flow improves the physical properties of the foam. It is effective and extremely suitable. The conditions may be such that the air bubble dispersion liquid is poured into the mold and immediately placed in a heating oven for post cure, and heat is not directly transferred to the reaction components even under such conditions, so the air bubble size does not increase. . It is preferable to carry out the curing reaction at normal pressure because the bubble shape becomes stable.

In the present invention, a known catalyst such as a tertiary amine type or organic tin type which accelerates the polyurethane reaction may be used. The type of catalyst and the amount of catalyst added are selected in consideration of the flow time of pouring into a mold having a predetermined shape after the mixing step.

The polyurethane resin foam constituting the polishing layer of the present invention can be manufactured by a batch system in which each component is weighed and put in a container and stirred, or a stirring device is used to produce a non-reactive gas with each component. May be continuously supplied and stirred, and a bubble dispersion liquid may be sent out to produce a molded product.

In the present invention, the hardness of the polishing pad polishing layer containing a surfactant is measured by a D-type rubber hardness tester.
It is preferably 45 or more and less than 65. D hardness is 45
If it is less than the above, the flattening characteristic is deteriorated, and if it is 65 or more, the flattening characteristic is good, but the uniformity is deteriorated.

In the present invention, for the purpose of improving the polishing uniformity of the object to be polished, the polishing pad is a cushion softer than the polishing layer in contact with the object to be polished and the polishing layer supporting the polishing layer. At least two layers may be configured. In this case, as the cushion layer, a fibrous non-woven fabric layer such as polyester non-woven fabric, nylon non-woven fabric, acrylic non-woven fabric, or a material obtained by impregnating these non-woven fabrics with urethane resin, a closed cell foam such as urethane resin or polyethylene resin is used. be able to. Among them, urethane-impregnated polyester nonwoven fabric, polyurethane foam or polyethylene foam is preferable in terms of easiness of production, inexpensiveness, stability of physical properties, etc., and polyurethane closed-cell foam is particularly preferable. By using the foam, it is possible to supply an inexpensive pad having excellent durability against repeated load. The polishing pad may have an adhesive layer (adhesive tape layer) in addition to the polishing layer and the cushion layer.

As a method of polishing a semiconductor wafer, a known polishing machine can be used and the polishing pad of the present invention can be mounted. As the polishing agent supplied between the polishing layer and the semiconductor wafer during polishing, any known polishing agent used for polishing a semiconductor wafer can be used without particular limitation. Specific examples thereof include abrasives such as ceria and silica. Also,
It is also suitable to use a commercially available silica slurry SS21 (manufactured by Cabot).

The semiconductor device is manufactured through the step of polishing the surface of the semiconductor wafer using the polishing pad. A semiconductor wafer is generally a silicon wafer on which a wiring metal and an oxide film are laminated. The method and apparatus for polishing a semiconductor wafer are not particularly limited. For example, as shown in FIG. 1, a polishing surface plate 2 for supporting a polishing pad 1, a support base (polishing head) 4 for supporting a semiconductor wafer 3 and a wafer are used. Is performed by using a backing material for performing uniform pressurization and a polishing device provided with a polishing agent supply mechanism 5. The polishing pad 1 is attached to the polishing platen 2 by sticking it with a double-sided tape. The polishing surface plate 2 and the support base 4 are arranged such that the polishing pad 1 and the semiconductor wafer 3 supported by the polishing surface plate 2 and the support base 4 face each other, and the rotation shafts 6 and 7 are provided respectively.
Is equipped with. In addition, the semiconductor wafer 3 is provided on the support base 4 side.
A pressing mechanism for pressing the polishing pad 1 against the polishing pad 1 is provided. At the time of polishing, the semiconductor wafer 3 is pressed against the polishing pad 1 while rotating the polishing platen 2 and the support base 4, and polishing is performed while supplying the slurry. The flow rate of the slurry, the polishing load, the number of rotations of the polishing platen, and the number of rotations of the wafer are not particularly limited and may be adjusted appropriately.

As a result, the protruding portion of the surface of the semiconductor wafer 3 is removed and the surface is polished flat. Then, a semiconductor device is manufactured by dicing, bonding, packaging, and the like. The semiconductor device is used for an arithmetic processing unit, a memory and the like.

[0058]

EXAMPLES Examples which specifically show the constitution and effects of the present invention will be described below. [Evaluation Method] 1) Dynamic Friction Coefficient Measurement Method An apparatus for measuring the dynamic friction coefficient is shown in FIG. 2A is an overall view, and FIG. 2B is a configuration diagram of the measurement sample 20.
A glass plate (high heat resistance glass Pyrex (manufactured by Corning, # 7740, 150) placed on the gantry 11 was used for the measurement.
mm × 250 mm × 5 mm)) 10 and the sheet 9 constituting the polishing layer is placed on the double-sided tape (double tack tape # 5).
782, Sekisui Chemical Co., Ltd. 22 cushion layer (low-density polyethylene foam having a specific gravity of 0.17, thickness: 1.2)
7 mm) 23, and a double sided tape 535A (made by Nitto Denko) 24 for fixing a resin printing plate is further used to bond the cushion layer 23 and the weight 8 to each other to obtain a measurement sample 20 on which the weight 8 is placed. And the friction measuring device 1
In 3, the polishing layer constituting sheet 9 of the measurement sample 20 is moved by pulling it in the direction of arrow 12 while sliding on the glass plate 10 and measuring the friction coefficient. The dynamic friction coefficient is the average of the minimum value and the maximum value of the dynamic friction force after showing the static friction force when the measurement sample 20 is moved by 10 cm in the chart of the friction force measured by the above friction coefficient device, 4.4 kg.
It is calculated by dividing by f. The size of the polishing layer constituent sheet (polyurethane resin foam sheet) is 5 cm x 8 c
m, the weight 8 for load has a weight of 4.4 kg and a bottom surface of 8 c
mx 5 cm, the moving speed of the measurement sample 20 is 20
cm / min, measurement time is 30 seconds. Friction measuring device 13
Tensilon RTM-100 (TOYO BALD
WIN) and environmental conditions are temperature (23 ± 2)
C. and humidity were (50 ± 6)% RH. When the polishing layer has grooves, five measurement samples are taken out from an arbitrary place (uniformly from the whole so as not to be biased at some places), the dynamic friction coefficient is measured, and the average value is obtained. .

2) Evaluation of Polishing Characteristics The polishing characteristics were evaluated using SPP600S manufactured by Okamoto Machine Tool Co., Ltd. as a polishing apparatus. An interference-type film thickness measuring device manufactured by Otsuka Electronics Co., Ltd. was used for measuring the film thickness of the oxide film. The polishing conditions are a polishing load of 350 g / cm ² and a polishing plate rotation speed of 3
The rotation speed is 5 rpm and the wafer rotation speed is 30 rpm. When polishing, silica slurry SS21 (made by Cabot)
Was dropped at a flow rate of 150 ml / min during polishing. In the evaluation of the polishing characteristics, after depositing a thermal oxide film of 0.5 μm on an 8-inch silicon wafer, the following patterning (270/30 and 30/270 lines / spaces) was performed, and then p- An oxide film was deposited by TEOS to a thickness of 1 μm, a patterned wafer having an initial step difference of 0.5 μm was manufactured, and the wafer was polished under the above conditions to evaluate two step differences. One is a local step, which is two wide
The 70 μm line is the step difference in the pattern lined up in the 30 μm space, and the other is the scraping amount of the bottom portion of the pattern space in which the 30 μm line is lined up in the 270 μm space. The average polishing rate is 27
The average value of the 0 μm line portion and the 30 μm line portion was taken as the average polishing rate.

3) Method of measuring compressibility The compressibility was measured by using the produced polyurethane resin foam sheet (material for polishing layer) with a cylindrical indenter having a diameter of 5 mm.
A load was applied at 25 ° C. by TMA manufactured by Mac Science Co., Ltd., and T1 and T2 were measured. Compressibility (%) = [(T1−T2) / T1] × 100 where T1 is 30 kPa (300 g /
cm ² load of stress) represents the thickness of the sheet when held for 60 seconds, T2 represents the thickness of the sheet when held 60 seconds the load stress of 180kPa from the state T1.

4) Surface Roughness Measuring Method The surface roughness was measured by cutting the obtained polyurethane resin foam sheet into a size of 10 × 10 mm and using a surface shape measuring device (P15, manufactured by KLA Tencor Co., Ltd.). It was measured. The measurement conditions are scan length 2.5 mm, cutoff length 2.5 mm, scan speed 20 μm / sec, 50H.
Z sampling and needle pressure 2 mg. The surface roughness was calculated by measuring five arbitrary points and calculating the average value. In addition,
When the polyurethane resin foam sheet has grooves,
The surface roughness is measured except for the groove portion.

5) Average Cell Diameter Measurement Method To measure the average cell diameter, a section of the obtained foam polishing layer was cut with a microtome, and a microscopic image of the section was taken by an image processing apparatus Image Analyzer V10 (manufactured by Toyobo Co., Ltd.). Then, the bubbles were separated, the bubble particle size distribution per unit area was measured, and the average bubble diameter was calculated.

6) Shore D hardness measurement method: Measured according to JIS K6253. 1. Cut 6 pieces of the polishing layer sliced into 27 mm thick into 1.5 cm square pieces.
The sample cut out is 23.5 degrees ± 2 ° C x 50% humidity
X Hold for 16 hours and then stack 6 samples, D
Set on the hardness tester. After puncturing a sample in which six D hardness meter needles are stacked, one minute later, the D hardness meter pointer is read.

7) Specific gravity measurement The specific gravity was measured according to JIS Z8807-1976. 4c
A polishing layer cut out in a rectangular shape (thickness: arbitrary) of m × 8.5 cm was used as a sample for measuring specific gravity, and the temperature was 23 ° C. ± 2 ° C. and the humidity was 5
It was allowed to stand for 16 hours in an environment of 0% ± 5%. A specific gravity meter (manufactured by Sartorius) was used for the measurement, and the specific gravity was measured.

8) Analysis of Surfactant 15 mg of the polishing layer was weighed and dissolved in dimethyl sulfoxide-d ₆ (0.7 ml) at 130 ° C. The solution was spun down by centrifugation, 5 mg of tetrachloroethane was added to the supernatant, and a proton NMR device (Bruker
Manufactured by AVANCE-500, 500 MHz), measuring temperature 80 ° C, detection pulse 15 °, FID uptake time 4
Seconds, repeat time 9 seconds, and measurement range -2 to 14 ppm
The spectrum was measured under the following conditions. The window function at the time of Fourier transform is not used. The content of the surfactant was quantified from the area of the peak based on tetrachloroethane appearing near 6.8 ppm and the peak based on the methyl group bonded to Si near 0 ppm in the obtained spectrum.

[Production of Polishing Layer] (Example 1) Toluene diisocyanate (2,4-body /
2,6-body = 80/20 mixture :) 1000 parts by weight,
4,4'-dicyclohexylmethane diisocyanate 1
68 parts by weight, 1678 parts by weight of polytetramethylene glycol (number average molecular weight: 1012), and 150 parts by weight of 1,4-butanediol were mixed and heated and stirred at 80 ° C. for 150 minutes to prepare an isocyanate-terminated prepolymer (isocyanate equivalent). : 2.20 meq / g) was prepared.

100 parts by weight of the isocyanate-terminated prepolymer and 3 parts by weight of a silicon-based surfactant (SH192, manufactured by Toray Dow Corning Co., Ltd.) were mixed in a container, and the mixture was heated to 80 ° C.
Adjusted to. Here, violently 90 to take in air bubbles.
4, which was previously melted at 120 ° C. with stirring at 0 rpm
29 parts by weight of 4'-methylenebis (o-chloroaniline) were added. After stirring for about 1 minute, the mixed solution was put into a pan-type open mold and post-cured at 110 ° C. for 6 hours in an oven to obtain a polyurethane resin foam block. This polyurethane resin foam block had an average cell diameter of 40 μm, a specific gravity of 0.86, a Shore D hardness of 52, and a compression rate of 2.0%. This polyurethane resin foam block was sliced using a band saw type slicer (manufactured by Fecken) to obtain a polyurethane resin foam sheet (thickness: 1.27 mm). Then, the surface of the sheet on the polishing surface side was dressed using sandpaper of abrasive grain count # 120 (manufactured by Noritake Super Abrasive Co., Ltd.) to prepare the polishing layer (without grooves) by adjusting the surface shape. The surface roughness of the polishing surface of the polishing layer was 9 μm, and the dynamic friction coefficient was 0.2.

As the cushion layer, polyethylene foam (Toray Pef, Toray Pef, Shore A hardness: 37) manufactured by Toray Industries, Inc. was processed by sandpaper to a thickness of 0.8 mm and then corona-treated on both sides.

A double-sided tape (double tack tape # 5782, manufactured by Sekisui Chemical Co., Ltd.) for the polishing layer and the cushion layer.
A polishing pad was produced by laminating the polishing pads.

(Example 2) A polishing pad was produced in the same manner as in Example 1 except that sandpaper of abrasive grain count # 240 (manufactured by Noritake Super Abrasive Co., Ltd.) was used. The surface roughness of the polishing layer (without grooves) on the polishing surface side is 7 μm,
The dynamic friction coefficient was 0.28.

Example 3 A polishing pad was prepared in the same manner as in Example 1 except that sandpaper of abrasive grain count # 400 (manufactured by Noritake Super Abrasive Co., Ltd.) was used. The surface roughness of the polishing surface of the polishing layer (without grooves) is 4.4μ.
m, the coefficient of dynamic friction was 0.33.

Example 4 An isocyanate-terminated prepolymer was prepared in the same manner as in Example 1. 100 parts by weight of the isocyanate-terminated prepolymer and a silicone-based surfactant (SH19 manufactured by Toray Dow Corning Incorporated) were placed in a container.
2) 3 parts by weight were mixed and adjusted to 80 ° C. here,
29 parts by weight of 4,4′-methylenebis (o-chloroaniline) previously melted at 120 ° C. was added while stirring vigorously at 900 rpm so as to take in bubbles. About 45
After stirring for 2 seconds, the mixed solution was put into a pan-type open mold and post-cured at 110 ° C. for 6 hours in an oven to obtain a polyurethane resin foam block. This polyurethane resin foam block has an average cell diameter of 75 μm,
The specific gravity was 0.9, the Shore D hardness was 56, and the compression ratio was 1.1. Then, a polishing pad was produced in the same manner as in Example 1 except that sandpaper of abrasive grain count # 400 was used. The surface roughness of the polishing surface of the polishing layer (without grooves) is 7.
It was 4 μm and the dynamic friction coefficient was 0.37.

Example 5 An isocyanate-terminated prepolymer was prepared in the same manner as in Example 1. 100 parts by weight of the isocyanate-terminated prepolymer and a silicone-based surfactant (SH19 manufactured by Toray Dow Corning Incorporated) were placed in a container.
2) 3 parts by weight were mixed and adjusted to 80 ° C. here,
29 parts by weight of 4,4′-methylenebis (o-chloroaniline) previously melted at 120 ° C. was added while stirring vigorously at 900 rpm so as to take in bubbles. About 90
After stirring for 2 seconds, the mixed solution was put into a pan-type open mold and post-cured at 110 ° C. for 6 hours in an oven to obtain a polyurethane resin foam block. This polyurethane resin foam block has an average cell diameter of 30 μm,
The specific gravity was 0.78, the Shore D hardness was 50, and the compression ratio was 2.3. Then, a polishing pad was produced in the same manner as in Example 1 except that sandpaper of abrasive grain count # 400 was used. The surface roughness of the polishing layer (without grooves) on the polishing surface side is 5
μm, the coefficient of dynamic friction was 0.3.

Example 6 A polishing pad was produced in the same manner as in Example 1 except that the amount of the silicon-based surfactant added was 5 parts by weight and the sandpaper of abrasive grain count # 400 was used. Polyurethane resin foam has an average cell diameter of 2
It was 5 μm, specific gravity 0.77, Shore D hardness 48, and compression rate 2.5. The surface roughness of the polishing layer (without grooves) on the polishing surface side was 3.6 μm, and the dynamic friction coefficient was 0.55.

Example 7 A polishing pad was produced in the same manner as in Example 1 except that the amount of the silicon-based surfactant added was 1 part by weight and the sandpaper of abrasive grain count # 400 was used. Polyurethane resin foam has an average cell diameter of 5
It was 0 μm, specific gravity 0.87, Shore D hardness 54, and compression rate 1.6. The surface roughness of the polishing surface of the polishing layer (without grooves) was 6.5 μm, and the dynamic friction coefficient was 0.31.

Example 8 The diameter of the polishing layer obtained in Example 1 on the side of the polishing surface was 1.6 m using a punching machine.
23 holes / m ² formed at 5 mm intervals (groove area 8
%) Was used to prepare a polishing pad in the same manner as in Example 1. The surface roughness of the polishing surface of the polishing layer was 9 μm, and the coefficient of dynamic friction was 0.18.

(Example 9) The surface of the polishing layer obtained in Example 1 on the side of the polishing surface was 0.25 mm in width by using a groove processing device.
A polishing pad was produced in the same manner as in Example 1 except that concentric circular grooves having a depth of 0.4 mm and a pitch of 1.5 mm were formed (groove area: 17%). The surface roughness of the polishing surface of the polishing layer was 9 μm, and the dynamic friction coefficient was 0.17.

(Comparative Example 1) A polishing pad was produced in the same manner as in Example 1 except that sandpaper of abrasive grain count # 1200 (manufactured by Noritake Super Abrasive Co., Ltd.) was used. The surface roughness of the polishing surface of the polishing layer (without grooves) is 2 μm,
The dynamic friction coefficient was 0.78.

(Comparative Example 2) A polishing pad was produced in the same manner as in Example 1 except that sandpaper of abrasive grain count # 60 (manufactured by Noritake Super Abrasive Co., Ltd.) was used.
The surface roughness of the polishing layer (without grooves) on the polishing surface side was 15 μm, and the dynamic friction coefficient was 0.08.

Comparative Example 3 An isocyanate-terminated prepolymer was prepared by the same method as in Example 1. 100 parts by weight of the isocyanate-terminated prepolymer and a silicone-based surfactant (SH19 manufactured by Toray Dow Corning Incorporated) were placed in a container.
2) 3 parts by weight were mixed and adjusted to 80 ° C. here,
29 parts by weight of 4,4′-methylenebis (o-chloroaniline) previously melted at 120 ° C. was added while stirring vigorously at 900 rpm so as to take in bubbles. About 25
After stirring for 2 seconds, the mixed solution was put into a pan-type open mold and post-cured at 110 ° C. for 6 hours in an oven to obtain a polyurethane resin foam block. This polyurethane resin foam block has an average cell diameter of 140μ.
m, specific gravity 0.9, Shore D hardness 55, and compression rate 1.0
Met. Then, a polishing pad was produced by the same method as in Example 1. The surface roughness of the polishing surface of the polishing layer (without grooves) was 11 μm, and the dynamic friction coefficient was 0.75.

[0081]

[Table 1] As is clear from Table 1, in the case of a polishing pad in which the polishing layer made of a polyurethane resin foam has a dynamic friction coefficient of 0.1 to 0.7 (Examples 1 to 9), a polishing rate sufficient for practical use is obtained. In addition, a dechuck error does not occur. On the other hand, in the case of the polishing pad in which the dynamic friction coefficient of the polishing layer is not within the above range (Comparative Examples 1 to 3), a dechuck error occurs or the polishing rate is not sufficient and the polishing rate is kept high. It has not been possible to achieve the object of the present invention to suppress the occurrence of dechuck errors.

[Brief description of drawings]

FIG. 1 is a schematic view showing a semiconductor polishing apparatus.

FIG. 2 is a schematic diagram showing a method of measuring a dynamic friction coefficient.

─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masahiko Nakamori 1-1-1 Katata, Otsu City, Shiga Toyo Spinning Co., Ltd. (72) Inventor Kazuyuki Ogawa 1-17-18 Edobori, Nishi-ku, Osaka City, Osaka Prefecture No. Toyo Tire & Rubber Co., Ltd. (72) Inventor Jun Kazuno 1-17-18 Edobori, Nishi-ku, Osaka City, Osaka Prefecture Toyo Tire & Rubber Co., Ltd. (72) Takeshi Kimura 1-1-17 Edobori, Nishi-ku, Osaka City, Osaka No. 18 in Toyo Tire & Rubber Co., Ltd. (56) Reference JP 2001-89548 (JP, A) JP 2000-178374 (JP, A) JP 2001-176829 (JP, A) JP 2002-226537 (JP , A) JP 2002-192455 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 18/00-18/87 C08J 5/14 C09K 3/14 H01L 21/304 B24B 37/00

Claims (4)

(57) [Claims] 1. A polishing layer comprising a polyurethane resin foam, the polishing layer having a surface roughness of 3 to 10 μm, and the polishing layer having a flat surface.
A semiconducting device having a uniform cell diameter of 20 to 90 μm and a dynamic friction coefficient of the polishing layer surface of 0.1 to 0.7.
Polishing pad for polishing body wafers . 2. The semiconductor wafer according to claim 1 , wherein the polyurethane resin foam contains 0.05 to 5 wt% of a silicone-based surfactant which is a copolymer of polyalkylsiloxane and polyether. Polishing pad for polishing. 3. A method of manufacturing a polishing pad from a polyurethane resin foam, the method comprising the steps of slicing a block made of polyurethane resin foam into a sheet to prepare a polyurethane resin foam sheet, and the polyurethane resin foam. 3. The method according to claim 1 , further comprising a step of dressing at least a polishing surface side of the sheet.
Manufacturing method of polishing pad for polishing semiconductor wafer . 4. The semiconductor wafer polishing according to claim 1 or 2.
Of manufacturing a semiconductor device, including a step of polishing a surface of a semiconductor wafer using a polishing pad for use in a semiconductor device.