WO2010032715A1

WO2010032715A1 - Polishing pad

Info

Publication number: WO2010032715A1
Application number: PCT/JP2009/066046
Authority: WO
Inventors: 加藤　充; 菊池　博文; 知大岡本; 晋哉加藤
Original assignee: 株式会社クラレ
Priority date: 2008-09-17
Filing date: 2009-09-14
Publication date: 2010-03-25
Also published as: TW201021972A

Abstract

Disclosed is a polishing pad comprising at least a polishing layer. The polishing pad is characterized in that the polishing pad has grooves open to the surface of the polishing side of the polishing layer and holes open to the surface of the polishing side of the polishing layer, the area of the opening per hole is not less than 0.05 mm², and the depth of the grooves, the depth of the holes, and the thickness of the polishing layer satisfy formula (1): (1) Z>X>Y wherein X represents the depth of the grooves; Y represents the depth of the holes; and Z represents the thickness of the polishing layer. The polishing pad is particularly useful, for example, for chemimechanical polishing of, for example, an insulating film such as an oxide film or a metal film formed on a semiconductor wafer, can realize a high polishing speed, high polishing evenness and flattening properties, is less likely to cause scratching, and causes no significant change in polishing properties even when the polishing is continued for a long period of time.

Description

Polishing pad

The present invention relates to a polishing pad useful for polishing a semiconductor wafer or the like.

Conventionally, as a polishing pad used when mirror-finishing a semiconductor wafer or flattening unevenness of an insulating film or a conductor film at the time of manufacturing a semiconductor device, a relatively soft non-woven fabric impregnated with polyurethane resin is used. A polishing pad or a polishing pad made of foamed polyurethane is used (see, for example, Patent Documents 1 to 4).
Of these, in semiconductor device manufacturing applications, the polishing rate of convex portions that are portions to be polished is increased, while the polishing rate of concave portions that are portions that should not be polished is reduced. In order to achieve this required performance, generally, a relatively hard polishing pad made of polyurethane foam is employed.
Normally, the polishing side surface of this polishing pad is supplied with a uniform and sufficient supply of polishing slurry to the surface of the wafer to be polished, discharge of polishing debris that causes scratches on the wafer surface, and adsorption of the polishing pad Grooves and holes are formed for the purpose of preventing wafer breakage (see, for example, Patent Documents 2 to 4 above).

However, when grooves or holes are formed alone on the surface of the polishing pad, it is difficult to satisfy all of the above objects.
That is, when only the grooves are formed on the surface of the polishing pad, the concentric grooves that are generally employed tend to cause scratches on the wafer surface because of the low dischargeability of polishing debris. Also, if polishing is performed under conditions of low-pressure and high-speed rotation to suppress the generation of scratches, the pad / wafer is easily lubricated with fluid, and the polishing rate is reduced, or the polishing rate does not vary at various points on the wafer. There is a tendency for polishing uniformity to decrease. In addition, in the grid-like grooves, although the polishing dust is well discharged, the polishing slurry tends to be excessively discharged, and it becomes difficult to supply the polishing slurry uniformly and sufficiently to the wafer surface. As a result, the running cost tends to increase.
On the other hand, when only a hole is formed on the surface of the polishing pad, as in the case of the concentric groove, scratching is likely to occur on the wafer surface because of low polishing dust discharge. In addition, since the fluidity of the polishing slurry on the polishing pad is inferior, the supply property of the polishing slurry to the wafer surface is lowered, and the polishing rate and the polishing uniformity are likely to be lowered. In order to solve the above problem, a groove and a hole are also used in combination (see Patent Documents 2 and 4), but all of the above-mentioned problems cannot be satisfied.

Also, in the polishing pad for semiconductor device manufacturing use, even if a large number of wafers are polished for a long time, the change in polishing performance is small and long life is required from the viewpoint of cost reduction, quality control, etc. With conventional polishing pads, the polishing performance tends to change when polishing is continued for a long time, and there is room for further improvement in order to extend the life of the polishing pad.

Japanese Patent Laid-Open No. 5-8178 JP-A-9-117855 JP 2000-178374 A JP 2002-160153 A

The present invention provides a high polishing rate, excellent polishing uniformity and flattening performance, excellent polishing performance such as less scratching, and small change in polishing performance even if polishing is continued for a long time. An object is to provide a long-life polishing pad.

In order to achieve the above object, the present inventors have conducted intensive studies. As a result, in a polishing pad having a polishing layer in which grooves and holes are formed, it has been found that the above object can be achieved by making the depth of the grooves larger than the depth of the holes, and further studies are made based on the findings. The present invention has been completed.

That is, the present invention
[1] A polishing pad having at least a polishing layer,
A groove opened on the polishing side surface of the polishing layer, and a hole opened on the polishing side surface of the polishing layer;
The opening area per one of the holes is 0.05 mm ² or more,
A polishing pad, wherein the depth of the groove, the depth of the hole, and the thickness of the polishing layer satisfy the following formula (1):
(1) Z>X> Y
(In the formula, X represents the depth of the groove, Y represents the depth of the hole, and Z represents the thickness of the polishing layer.)
[2] The polishing pad according to [1], wherein the depth of the groove and the depth of the hole satisfy the following formula (2):
(2) XY ≧ 0.1
(In the formula, X represents the depth of the groove, Y represents the depth of the hole, and the unit of length is mm.)
[3] The polishing pad according to [1] or [2], wherein the depth of the groove satisfies the following formulas (3) to (5):
(3) X ≧ 0.5
(4) 0.50 × Z ≦ X ≦ 0.90 × Z
(5) ZX ≧ 0.2
(In the formula, X represents the depth of the groove, Z represents the thickness of the polishing layer, and the unit of length is mm.)
[4] The polishing pad according to any one of [1] to [3], wherein the hole depth satisfies the following formulas (6) to (8):
(6) Y ≧ 0.2
(7) 0.30 × Z ≦ Y ≦ 0.85 × Z
(8) ZY ≧ 0.4
(In the formula, Y represents the depth of the hole, Z represents the thickness of the polishing layer, and the unit of length is mm.)

[5] The polishing pad according to any one of [1] to [4] above, wherein the groove has a lattice shape.
[6] A total volume (a) of grooves opened on the polishing side surface of the polishing layer and a total volume (b) of holes opened on the polishing side surface of the polishing layer and having an opening area of 0.05 mm ² or more. The polishing pad according to any one of the above [1] to [5], wherein the ratio (a / b) is in the range of 50/50 to 90/10;
[7] The polishing pad according to any one of the above [1] to [6], wherein a cushion layer is laminated on a surface opposite to the polishing side surface of the polishing layer,
[8] The polishing pad according to any one of [1] to [7], wherein the polishing layer has a non-foamed structure,
[9] A method for polishing a semiconductor wafer using the polishing pad of any one of [1] to [8] above,
[10] A method of manufacturing a semiconductor device using the polishing pad according to any one of [1] to [8].

According to the present invention, a high polishing rate can be obtained, excellent polishing uniformity and planarization performance, excellent polishing performance such as less scratching, and even if polishing is continued for a long time, the polishing performance changes. A small long-life polishing pad can be obtained.

(A) is a schematic diagram which shows the lattice-like groove | channel of a polishing pad, (b) is a schematic diagram which shows the cross-sectional shape of a groove | channel.

Hereinafter, the present invention will be described in detail.
The polishing pad of the present invention has at least a polishing layer, and further has a groove opened on the polishing side surface of the polishing layer and a hole opened on the polishing side surface of the polishing layer.
When only a groove is provided on the polishing side surface of the polishing layer as in a conventional polishing pad, for example, a closed groove shape having no discharge path to the outside of the polishing pad, such as a concentric groove, has a low polishing dust discharging property. Therefore, scratches are likely to occur on the wafer surface. In addition, when polishing is performed under the conditions of low pressure and high speed rotation in order to suppress the occurrence of scratches, the pad / wafer is likely to be fluid lubricated, and the polishing rate and polishing uniformity tend to decrease. On the other hand, in a grid-like groove where there is a discharge path to the outside of the polishing pad, polishing slurry is easily discharged, but polishing slurry is also easily discharged, so the polishing slurry is evenly and sufficiently supplied to the wafer surface. It becomes difficult to increase the supply amount of the polishing slurry, and as a result, the running cost tends to increase.
Further, when only the hole is provided on the polishing side surface of the polishing pad, scratches are likely to be generated on the wafer surface due to the low dischargeability of polishing debris as in the case of concentric grooves. In addition, the flowability of the polishing slurry on the polishing side surface is inferior, so that the supply of the polishing slurry to the wafer surface is reduced and the polishing rate and polishing uniformity are reduced.
The polishing pad of the present invention can improve the polishing performance such as high polishing rate, excellent polishing uniformity, low scratch and the like in a well-balanced manner by having both grooves and holes opened on the polishing side surface of the polishing layer. .

In addition to having both grooves and holes, the polishing pad of the present invention must satisfy the following (1), where X is the depth of the groove, Y is the depth of the hole, and Z is the thickness of the polishing layer. is there.
(1) Z>X> Y
(In the formula, X represents the depth of the groove, Y represents the depth of the hole, and Z represents the thickness of the polishing layer.)
As a result of investigations by the present inventors, in a polishing pad having a conventional through hole, the polishing slurry reaches the adhesive layer on the back surface of the polishing pad during polishing, and the adhesive force changes during polishing. It was found that the performance was degraded. Therefore, in the polishing pad of the present invention, the deterioration of the polishing performance during polishing caused by the through hole is suppressed by not forming a portion penetrating the portion on the side opposite to the polishing side surface.
In the present specification, the groove means that the distance (A) between the two most distant points of the continuous openings is 5 mm or more, and [the area of the opening / the area of the circle with the diameter A] is 0.4. It is the following opening, and the hole means an opening other than the groove. Further, in the present specification, the depth of the groove is the distance from the polishing side surface (plane) to the deepest part of the groove, and the depth of the hole is the distance from the polishing side surface (plane) to the deepest part of the hole. Means.

The polishing pad of the present invention requires that the depth of the groove is larger than the depth of the hole.
If the depth of the hole is deeper than the groove, polishing scraps tend to accumulate in the hole, and the accumulated polishing scraps may come out on the polishing surface during polishing and cause scratches. Further, in the case of the through hole (when Z = Y> X), there is a problem that the polishing slurry reaches the adhesive layer on the back surface of the polishing layer during polishing and changes its adhesive force, and the polishing performance is likely to change over time. is there.
Furthermore, when the polishing layer is made of a hard material and has a non-foamed structure, processing is difficult compared to foamed resin, so when forming the through hole, burrs are generated or deformed around the through hole. Cheap. Even with non-through holes, if the thickness of the polishing layer at the bottom of the hole is reduced to form a deep hole, the back side of the polishing layer tends to swell at the hole when the hole is formed by cutting, etc. Unevenness is likely to occur, and both polishing uniformity and planarization performance tend to decrease. When grooves and holes are formed by cutting, generally, the back side of the polishing layer is more easily deformed at the hole portion than the groove, so that the depth of the hole needs to be smaller than the depth of the groove.

Furthermore, it is preferable that the depth of a groove | channel and the depth of a hole satisfy | fill following formula (2) from a viewpoint which balances the lifetime of a polishing pad, and the outstanding polishing performance.
(2) XY ≧ 0.1
(In the formula, X represents the depth of the groove, Y represents the depth of the hole, and the unit of length is mm.)
That is, the difference between the depth of the groove and the depth of the hole is preferably 0.1 mm or more, and more preferably 0.15 mm or more. The difference between the depth of the groove and the depth of the hole is preferably 0.5 mm or less, more preferably 0.4 mm or less, and further preferably 0.3 mm or less.

In the polishing pad of the present invention, the depth of the groove and the thickness of the polishing layer preferably satisfy the following formulas (3) to (5).
(3) X ≧ 0.5
(4) 0.50 × Z ≦ X ≦ 0.90 × Z
(5) ZX ≧ 0.2
(In the formula, X represents the depth of the groove, Z represents the thickness of the polishing layer, and the unit of length is mm.)
When the above formula (3) is satisfied, that is, by setting the groove depth to 0.5 mm or more, a change in polishing performance due to abrasion of the polishing pad can be suppressed, and the life of the polishing pad tends to be long. There is. The depth of the groove is more preferably 0.55 mm or more, and further preferably 0.6 mm or more.
Further, when the relationship of the above formula (4) is satisfied, that is, when the depth of the groove is 50 to 90% of the thickness of the polishing layer, or when the cushion layer is laminated on the lower layer, the polishing uniformity and flattening are achieved. It is preferable because performance can be made compatible. When the depth of the groove is less than 50% of the thickness of the polishing layer, the polishing uniformity tends to be lowered and the life of the polishing pad tends to be shortened. On the contrary, when the depth of the groove is larger than 90% of the thickness of the polishing layer, the planarization performance tends to be lowered. More preferably, the depth of the groove is 55 to 85% of the thickness of the polishing layer.
Furthermore, when the relationship of the above formula (5) is satisfied, that is, when the difference between the thickness of the polishing layer and the depth of the groove is 0.2 mm or more, the thickness of the polishing layer at the bottom of the groove is secured to some extent. Even when a cushion layer is laminated on the lower layer, it is easy to ensure flattening performance by suppressing excessive deformation of the polishing layer. The difference between the thickness of the polishing layer and the depth of the groove is more preferably 0.25 mm or more.

In the polishing pad of the present invention, the hole depth preferably satisfies the following formulas (6) to (8).
(6) Y ≧ 0.2
(7) 0.30 × Z ≦ Y ≦ 0.85 × Z
(8) ZY ≧ 0.4
(In the formula, Y represents the depth of the hole, Z represents the thickness of the polishing layer, and the unit of length is mm.)
By satisfying the above formula (6), that is, by setting the hole depth to 0.2 mm or more, a change in polishing performance due to abrasion of the polishing pad can be suppressed, and the life of the polishing pad tends to be long. There is. The depth of the hole is more preferably 0.3 mm or more, and further preferably 0.4 mm or more.
Further, from the viewpoint of achieving both the life of the polishing pad, the polishing uniformity, and the planarization performance, the relational expression (7) is satisfied, that is, the hole depth is 30 to 85% of the thickness of the polishing layer. Preferably there is. When the depth of the hole is less than 30% of the thickness of the polishing layer, the life of the polishing pad tends to be shortened. On the contrary, if the depth of the hole is larger than 85% of the thickness of the polishing layer, the discharging property of the polishing debris from the hole becomes low, and the polishing debris accumulated in the hole comes out again with the abrasion of the polishing pad, There is a tendency for the occurrence of scratches to increase. The depth of the hole is more preferably 35 to 80% of the thickness of the polishing layer.
Furthermore, when the hole is formed by cutting or the like, it can be suppressed that the back side of the polishing layer swells at the bottom of the hole and unevenness in thickness occurs in the polishing layer, resulting in a decrease in polishing uniformity and planarization performance. From the viewpoint, it is preferable that the relational expression (8) is satisfied, that is, the difference between the thickness of the polishing layer and the depth of the hole is 0.4 mm or more. The thickness of the polishing layer and the depth of the hole More preferably, the difference is 0.45 mm or more.

As the shape (pattern) of the groove opened on the polishing side surface of the polishing layer, a known shape such as a lattice shape, a concentric circle shape, a spiral shape, a hexagonal shape, a triangular shape, or a combination thereof can be adopted. From the standpoint that scraps can be easily discharged out of the polishing pad and the ability to suppress the generation of scratches on the wafer surface is high, lattice-like grooves are preferable.
Further, the cross-sectional shape of the groove is preferably rectangular because the groove width does not change even when the polishing pad is worn and the polishing performance hardly changes.

The width of the groove is preferably in the range of 0.1 to 5 mm, since it is excellent in the balance between polishing dust discharge and polishing slurry retention. When the width of the groove is smaller than 0.1 mm, the polishing dust discharge property is lowered and scratches tend to be generated on the wafer surface. On the other hand, if the width of the groove is larger than 5 mm, the polishing slurry tends to be excessively discharged outside the polishing pad, and it tends to be difficult to supply the polishing slurry uniformly and sufficiently to the wafer surface. As a result, it is necessary to increase the supply amount of the polishing slurry, and the running cost tends to increase. The width of the groove is more preferably in the range of 0.15 to 4 mm, and still more preferably in the range of 0.2 to 3 mm.
Further, since the groove pitch is in the range of 1 to 20 mm, the polishing slurry can be supplied uniformly and sufficiently to the wafer surface, and the polishing pad can be further improved in polishing rate and polishing uniformity. preferable. The pitch of the grooves is more preferably in the range of 2 to 18 mm, and further preferably in the range of 3 to 16 mm.

The shape of the hole opened on the polishing side surface of the polishing pad is not particularly limited, and the shape of the opening on the polishing side surface of the polishing layer may be any of a circle, a triangle, a quadrangle, a hexagon, and the like. Further, the cross-sectional shape of the hole that appears when cut perpendicular to the polishing side surface of the polishing layer may be any of a rectangle, a trapezoid, a triangle, and the like. Among these, the hole processing is easy, and even if the polishing pad is worn, the hole area in the opening does not change and the polishing performance hardly changes. A hole having a circular opening shape on the polishing side surface and a rectangular cross-sectional shape that appears when the polishing layer is cut perpendicularly to the polishing side surface is preferable.
The distribution of the holes formed on the polishing side surface of the polishing pad is not particularly limited, but it is preferable that the holes are uniformly distributed on the polishing side surface, for example, when the grooves are in a lattice shape. And one having one or more holes formed in each lattice.

The area of the opening of the hole on the polishing side surface of the polishing layer is such that the polishing slurry can be supplied uniformly and sufficiently to the wafer surface, and from the viewpoint of easy hole processing, 0.05 mm ² or more, preferably within a range of 0.1 to 20 mm ² , more preferably within a range of 0.3 to 15 mm ² , and within a range of 0.5 to 12 mm ^2. More preferably it is.
The individual holes opened on the polishing side surface of the polishing layer may all have the same opening shape, cross-sectional shape and opening area, but some or all of them may have the same shape. They may be different from each other.

The ratio (a / b) between the total volume (a) of the grooves opening on the polishing side surface of the polishing layer and the total volume (b) of the holes opening on the polishing side surface of the polishing layer is 50/50 to 90 / It is preferable that it is within the range of 10 because it is particularly excellent in the balance between the holding property of the polishing slurry, the uniform supply property to the wafer surface, and the discharge property of polishing waste. When the ratio (a / b) is smaller than 50/50, the uniform supply of polishing slurry to the wafer surface and the discharge of polishing debris are reduced, the polishing rate and polishing uniformity are reduced, and scratches are formed on the wafer surface. It tends to occur easily. On the other hand, if the ratio (a / b) is greater than 90/10, the retention of the polishing slurry tends to decrease, and the polishing rate and polishing uniformity tend to decrease. The ratio (a / b) is more preferably in the range of 55/45 to 88/12, and still more preferably in the range of 60/40 to 86/14.

From the viewpoint of polishing performance and workability, the thickness of the polishing layer is preferably in the range of 0.7 to 1.6 mm, and preferably in the range of 0.75 to 1.5 mm. Is more preferable, and a range of 0.8 to 1.4 mm is even more preferable. If the thickness of the polishing layer is less than 0.7 mm, the polishing layer may be affected by the hardness of the surface plate of the polishing apparatus or the hardness of the cushion layer when the cushion layer is laminated on the lower layer. There is a tendency that the polishing performance is not stable with wear. On the other hand, if the thickness of the polishing layer is larger than 1.6 mm, the bending rigidity of the polishing pad will increase, and even if a cushion layer is laminated on the lower layer, the polishing layer will not be easily deformed, resulting in a decrease in polishing uniformity. There is.

The polishing pad of the present invention has a higher hardness of the polishing layer and exhibits more excellent planarization performance, and the abrasive grains in the polishing slurry are aggregated in the pores due to the absence of pores exposed on the side surfaces of the grooves and holes. The polishing layer preferably has a non-foamed structure from the standpoint that there is no risk of adhesion and generation of scratches on the wafer surface.

The D hardness of the polishing layer is preferably in the range of 50 to 80, more preferably in the range of 53 to 77, from the viewpoint of improving the planarization performance and suppressing the occurrence of scratches on the wafer surface. Preferably, it is in the range of 56 to 74. By measuring the D hardness of the material constituting the polishing layer, it can be regarded as the D hardness of the polishing layer.

The material constituting the polishing layer of the polishing pad of the present invention is not particularly limited, and a known synthetic or natural polymer may be used alone or in combination of two or more. Examples of the polymer used as the material for the polishing layer include polyethylene, polypropylene, polybutadiene, ethylene-vinyl acetate copolymer, butyral resin, polystyrene, polyvinyl chloride, acrylic resin, epoxy resin, polyurethane, polyester, polyamide, etc. Is mentioned. Among these, polyurethane is preferable because it is excellent in flattening performance and is particularly excellent in polishing performance such that scratches hardly occur on the wafer surface, and polymer diol, organic diisocyanate and chain extender are reacted. The thermoplastic polyurethane obtained by this is more preferable.

Examples of the polymer diol include polyether diols such as polyethylene glycol and polytetramethylene glycol; poly (nonamethylene adipate) diol, poly (2-methyl-1,8-octamethylene adipate) diol, and poly (2- Polyester diols such as methyl-1,8-octamethylene-co-nonamethylene adipate) diol, poly (methylpentamethylene adipate) diol; poly (hexamethylene carbonate) diol, poly (hexamethylene-co-2,2-dimethyl-) And polycarbonate diols such as 1,3-propylene carbonate) diol. These polymer diols may be used alone or in combination of two or more.

As the organic diisocyanate, any of organic diisocyanates conventionally used in the production of ordinary polyurethanes may be used. For example, hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, etc. Aliphatic or cycloaliphatic diisocyanates; aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,5-naphthylene diisocyanate . These organic diisocyanates may be used alone or in combination of two or more. Among these, 4,4'-diphenylmethane diisocyanate is preferable from the viewpoint of the abrasion resistance of the polishing pad from which it can be obtained.

And as said chain extender, you may use any of the chain extenders conventionally used for manufacture of the usual polyurethane. As the chain extender, it is preferable to use a low molecular weight compound having a molecular weight of 350 or less having two or more active hydrogen atoms capable of reacting with an isocyanate group, for example, ethylene glycol, diethylene glycol, 1,2-propanediol. 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6 -Hexanediol, 3-methyl-1,5-pentanediol, 1,4-bis (β-hydroxyethoxy) benzene, 1,4-cyclohexanediol, cyclohexanedimethanol (1,4-cyclohexanedimethanol, etc.), bis (Β-hydroxyethyl) terephthalate, 1,9-nonanediol, Diols such as pyroglycol; ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, octamethylenediamine, nonamethylenediamine, hydrazine, xylylenediamine, isophoronediamine, piperazine, o-phenylenediamine, m-phenylenediamine, Examples thereof include diamines such as p-phenylenediamine, adipic acid dihydrazide, isophthalic acid dihydrazide, 4,4′-diaminodiphenylmethane, and 4,4′-diaminodiphenyl ether. These chain extenders may be used individually by 1 type, and may use 2 or more types together. Among these, 1,4-butanediol and / or 1,4-cyclohexanedimethanol are preferable.

The thermoplastic polyurethane can be produced by a known method such as a prepolymer method or a one-shot method using the above polymer diol, organic diisocyanate and chain extender as raw materials. It is preferably produced by melt-kneading the above-mentioned polymer diol, organic diisocyanate and chain extender at a predetermined ratio in the absence, and is produced by a continuous melt polymerization method using a multi-screw extruder. It is more preferable. The use ratio of each component is appropriately determined in consideration of the physical properties to be imparted to the polishing layer made of thermoplastic polyurethane, such as abrasion resistance, but 1 mol of active hydrogen atoms contained in the polymer diol and the chain extender. On the other hand, it is preferable to use each component in such a ratio that the isocyanate group contained in the organic diisocyanate is 0.95 to 1.3 mol. When the ratio is less than 0.95 mol, the mechanical strength and abrasion resistance of the resulting polishing layer made of thermoplastic polyurethane tend to decrease, and when it exceeds 1.3 mol, the productivity of thermoplastic polyurethane and Storage stability tends to decrease. From the viewpoint of mechanical strength and abrasion resistance of the resulting polishing layer and productivity and storage stability of thermoplastic polyurethane, it is contained in organic diisocyanate with respect to 1 mol of active hydrogen atoms contained in polymer diol and chain extender. It is more preferable to use each component at a ratio of 0.96 to 1.1 mol of the isocyanate group, and it is even more preferable to use each component at a ratio of 0.97 to 1.05 mol.

The polishing layer may be formed from only the above-described polymer, but may contain other components other than the above-described polymer as long as the resulting polishing pad exhibits the effects of the present invention. Examples of such other components include a crosslinking agent, a filler, a crosslinking accelerator, a crosslinking aid, a softening agent, a tackifier, an anti-aging agent, a foaming agent, a processing aid, an adhesion promoter, and a crystal nucleus. Agent, heat stabilizer, weather stabilizer, antistatic agent, colorant, lubricant, flame retardant, flame retardant aid (antimony oxide, etc.), blooming inhibitor, mold release agent, thickener, antioxidant, conductive agent Etc. The content of the other components in the polishing layer is preferably 50% by mass or less, more preferably 20% by mass or less, and further preferably 5% by mass or less.

The method for producing the polishing layer is not particularly limited, and one or two or more kinds of polymers or polymer compositions described above, or a polymer composition in which the above-described other components are further blended as necessary. The sheet | seat which consists of a thing can be manufactured and a polishing layer can be manufactured from the said sheet | seat. The sheet can be produced by extruding the polymer or polymer composition with an extruder. Specifically, for example, using an extruder equipped with a T-die, the polymer or polymer composition can be produced. A method of melt-extruding a product can be employed. As an extruder, a single screw extruder, a twin screw extruder, etc. can be used. The sheet can also be produced by previously producing a block made of the polymer or polymer composition described above and slicing it.
If necessary, the obtained sheet can be processed into a desired size and shape by cutting, punching, cutting, or the like, or processed to a desired thickness by grinding or the like to form a polishing layer.

The formation method of the groove opened on the polishing side surface of the polishing layer is not particularly limited. Specifically, a method of forming a groove by cutting the above sheet; contacting the above sheet with a heated mold or metal wire, or irradiating a beam such as a laser beam, A method of forming a groove by dissolving, decomposing or volatilizing the part; using a mold having a convex part for forming the groove, and then pouring a melt of the polymer or polymer composition into the mold Examples of the method include a method of producing a sheet in which grooves are formed in advance by solidifying or pouring and curing an uncured polymer raw material.

Further, the method for forming the hole opened on the polishing side surface of the polishing layer is not particularly limited. Specifically, a method of forming the sheet by cutting using a mechanical means such as a drill; the sheet is brought into contact with a heated mold or metal wire, or irradiated with a light beam such as a laser beam. For example, a method of forming a hole by dissolving, decomposing, or volatilizing the part can be used. Among these, since the processing accuracy is good and the material constituting the polishing layer is not easily deteriorated by heat, it is preferably formed by cutting.

The polishing pad of the present invention may have a single layer structure consisting only of a polishing layer having the above-described grooves and holes on the polishing side surface, but in order to improve polishing uniformity within the wafer surface, It is preferable to laminate a cushion layer on the surface opposite to the polishing side surface. Lamination of the cushion layer can be performed using a known pressure-sensitive adhesive or adhesive. The cushion layer preferably has an A hardness of 30 to 90. The material of the cushion layer is not particularly limited. For example, an elastomer having a non-foamed structure or a foamed structure, or a nonwoven fabric impregnated with a resin can be used.

The polishing pad of the present invention can be used for chemical mechanical polishing together with a known polishing slurry. The polishing slurry contains, for example, a liquid medium such as water or oil; an abrasive such as silica, alumina, cerium oxide, zirconium oxide, or silicon carbide; a base, an acid, an oxidizing agent, a surfactant, a chelating agent, or the like. ing. Moreover, when performing chemical mechanical polishing, you may use lubricating oil, a coolant, etc. together with polishing slurry as needed.

Chemical mechanical polishing can be performed by using a known chemical mechanical polishing apparatus and bringing the surface to be polished and the polishing pad into contact with each other at a constant speed under a pressure for a certain period of time through a polishing slurry. It is preferable to condition the polishing pad using a dresser such as a diamond dresser before or during polishing. The article to be polished is not particularly limited and includes, for example, quartz, silicon, glass, optical substrate, electronic circuit board, multilayer wiring board, hard disk, semiconductor wafer, etc. The polishing pad of the present invention is a semiconductor wafer. Can be preferably used for polishing. In particular, when polishing a semiconductor wafer having a diameter of 6 inches or more, more preferably 8 inches or more, the relative speed with respect to the polishing pad is likely to be high at the time of polishing and the polishing performance is difficult to control due to the large area. Since the polishing pad of the invention has an excellent polishing performance and has a long life, the polishing pad can be preferably used for the purpose of polishing such a semiconductor wafer.

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these examples. In addition, each evaluation was implemented with the following method.

[D hardness of material]
According to JIS K7311, it measured on the conditions of measurement temperature 25 degreeC.

[Polishing performance]
The polishing pad was installed in a polishing apparatus “MIRRA” manufactured by Applied Materials, and a diamond dresser (diamond count # 200) manufactured by Mitsubishi Materials Corporation was used. While flowing distilled water at a rate of 200 mL / min, the dresser rotation speed was 100 rpm, the platen The surface of the polishing pad was ground for 30 minutes at a rotation speed of 50 rpm (hereinafter referred to as “conditioning”).

Next, 200 mL of a solution obtained by diluting the polishing slurry “GPL-C1010” made by Showa Denko Co., Ltd. 10 times with ion-exchanged water under the conditions of dresser rotation speed 100 rpm, platen rotation speed 80 rpm, head rotation speed 79 rpm and polishing pressure 24 kPa A silicon wafer with a diameter of 8 inches having a PETEOS (plasma promoted tetraethyloxysilane) film having a thickness of 1000 nm and no pattern on the surface was polished for 60 seconds while being conditioned while supplying at a rate of / min. Thereafter, the wafers were exchanged, and polishing and conditioning were repeated again to polish a total of nine wafers. After that, a convex width of 100 μm, a concave width of 100 μm, a pitch of 200 μm, an oxide film thickness of the convex portion of 600 nm, and an HDP (high density plasma) oxide film having a pattern with an initial step of 500 nm between the convex portion and the concave portion having a diameter of 8 inches. One silicon wafer was polished for 60 seconds under the same conditions as described above.

Next, in order to examine the polishing performance after the pad wear, after performing only conditioning for 25 hours (corresponding to the conditioning time for polishing 1500 wafers), silicon having a diameter of 8 inches having an unpatterned PETEOS film on the surface again. After nine wafers were polished under the same conditions as the above polishing conditions, one silicon wafer with a diameter of 8 inches having a patterned HDP oxide film on the surface was polished under the same conditions.

Of the wafers polished in total, the wafers having the PETEOS film polished on the 8th and 18th sheets on the surface, the film thickness of the PETEOS film before and after polishing was measured at 49 points on the wafer surface, The polishing rate at each point was determined. The average value of the 49 polishing rates was defined as the polishing rate (R), and the polishing uniformity was evaluated by the non-uniformity obtained by the following equation (7). The smaller the non-uniformity value, the more uniformly the PETEOS film is polished within the wafer surface, and the better the polishing uniformity.
Nonuniformity (%) = (σ / R) × 100 (7)
(However, σ: Standard deviation of polishing rate at 49 points, R: Average value of polishing rate at 49 points.)

Further, the number of defects having a size of 0.2 μm or more was measured using a defect inspection apparatus “ComPLUS” manufactured by Applied Materials Co., Ltd., on the wafers having PETEOS films polished on the ninth and nineteenth surfaces.
Further, with respect to the wafers having the HDP oxide films with the patterns polished on the 10th and 20th sheets, the respective polishing rates were obtained from the amount of change in the oxide film thickness at the convex part and the concave part at the center of the wafer. The higher the polishing rate of the convex portion and the lower the polishing rate of the concave portion, the more preferable because the planarization of the wafer surface can be achieved in a short time and with a smaller polishing amount.

[Production Example 1]
Production of thermoplastic polyurethane Polytetramethylene glycol with a number average molecular weight of 2000 [abbreviation: PTMG], Poly (2-methyl-1,8-octamethylene-co-nonamethylene adipate) diol with a number average molecular weight of 2000 [abbreviation: PNOA; Unit to 2-methyl-1,8-octamethylene unit = 7 to 3], 1,4-cyclohexanedimethanol [abbreviation: CHDM], 1,4-butanediol [abbreviation: BD], and 4 , 4′-diphenylmethane diisocyanate [abbreviation: MDI] in such a ratio that the mass ratio of PTMG: PNOA: CHDM: BD: MDI is 24.5: 10.5: 5.0: 12.5: 47.5 Used continuously in a twin-screw extruder that rotates coaxially with a metering pump, and performs continuous melt polymerization to thermoplasticity. To produce a polyurethane. The resulting thermoplastic polyurethane melt was continuously extruded into water as strands, and then chopped with a pelletizer to obtain pellets. The pellets were dehumidified and dried at 70 ° C. for 20 hours to produce a thermoplastic polyurethane.

[Example 1]
The thermoplastic polyurethane obtained in Production Example 1 was loaded into a single screw extruder, extruded from a T-die to form a 2 mm thick sheet, and then the surface of the obtained sheet was ground to a thickness of 0.9 mm A uniform sheet. The D hardness of this sheet was 63. Next, this sheet was cut out into a circular shape having a diameter of 51 cm, and a lattice-like groove (cross section) having a groove width of 1.0 mm, a groove depth of 0.65 mm, and a groove pitch (vertical and horizontal pitch) of 7.0 mm on one surface thereof. In addition, a hole having a diameter of 2.5 mm and a depth of 0.45 mm was formed by cutting using a drill in the center of each lattice of the lattice-shaped grooves. Next, a foamed polyurethane sheet (A hardness 48) having a thickness of 1.0 mm was bonded to the surface opposite to the surface on which the grooves and holes were formed with an adhesive tape to prepare a polishing pad having a laminated structure. The structure of the polishing layer of the obtained polishing pad is shown in Table 1 below.
As a result of evaluating the polishing performance by the above-mentioned method, as shown in Table 2 below, the polishing rate, the polishing uniformity and the flattening performance are excellent, the number of defects is small, and the change in the polishing performance when used for a long time is also observed. It was small.

[Example 2]
After obtaining a circular sheet having a thickness of 1.3 mm and a diameter of 51 cm in the same manner as in Example 1, a groove width of 0.5 mm, a groove depth of 0.9 mm, and a groove pitch (longitudinal and lateral) were formed on one surface thereof. Pitch) A 4.0 mm grid-like groove (cross-sectional shape is rectangular) is formed, and a hole with a diameter of 1.5 mm and a depth of 0.75 mm is cut using a drill in the center of each grid of the grid-like groove. Formed by. Next, a foamed polyurethane sheet (A hardness 48) having a thickness of 1.0 mm was bonded to the surface opposite to the surface on which the grooves and holes were formed with an adhesive tape to prepare a polishing pad having a laminated structure. The structure of the polishing layer of the obtained polishing pad is shown in Table 1 below.
As a result of evaluating the polishing performance by the above-mentioned method, as shown in Table 2 below, the polishing rate, the polishing uniformity and the flattening performance are excellent, the number of defects is small, and the change in the polishing performance when used for a long time is also observed. It was small.

[Example 3]
After obtaining a circular sheet having a thickness of 1.1 mm and a diameter of 51 cm in the same manner as in Example 1, a groove width of 1.0 mm, a groove depth of 0.8 mm, and a groove pitch (longitudinal and lateral) were formed on one surface thereof. (Pitch) 12.0 mm grid-like grooves (cross-sectional shape is rectangular), and for each grid of the grid-like grooves, four intermediate points of the line segment connecting the center of the grid and the corners of the four corners and the grid A hole having a diameter of 2.0 mm and a depth of 0.6 mm was formed by cutting using a drill at a total of five locations. Next, a foamed polyurethane sheet (A hardness 48) having a thickness of 1.0 mm was bonded to the surface opposite to the surface on which the grooves and holes were formed with an adhesive tape to prepare a polishing pad having a laminated structure. The structure of the polishing layer of the obtained polishing pad is shown in Table 1 below.
As a result of evaluating the polishing performance by the above-mentioned method, as shown in Table 2 below, the polishing rate, the polishing uniformity and the flattening performance are excellent, the number of defects is small, and the change in the polishing performance when used for a long time is also observed. It was small.

[Comparative Example 1]
In Example 1, a polishing pad having a laminated structure was produced in the same manner as in Example 1 except that the hole depth was 0.65 mm. The structure of the polishing layer of the obtained polishing pad is shown in Table 1 below.
As a result of evaluating the polishing performance by the above-described method, as shown in Table 2 below, the polishing rate, the polishing uniformity, and the planarization performance were inferior.

[Comparative Example 2]
In Example 1, a polishing pad having a laminated structure was produced in the same manner as in Example 1 except that the depth of the groove was 0.45 mm. The structure of the polishing layer of the obtained polishing pad is shown in Table 1 below.
As a result of evaluating the polishing performance by the above-described method, as shown in Table 2 below, the initial polishing rate, the polishing uniformity and the flattening performance were excellent, and the number of defects was small, but the polishing rate and the polishing were used when used for a long time. The uniformity decreased, the number of defects increased, and the polishing performance was insufficiently stable.

[Comparative Example 3]
In Example 2, a polishing pad having a laminated structure was produced in the same manner as in Example 2 except that the hole was a through hole (depth was 1.3 mm). The structure of the polishing layer of the obtained polishing pad is shown in Table 1 below.
As a result of evaluating the polishing performance by the above-described method, as shown in Table 2 below, the initial polishing rate, the polishing uniformity and the flattening performance were excellent, and the number of defects was small, but the polishing rate and the polishing were used when used for a long time. The uniformity decreased and the stability of the polishing performance was insufficient.

[Comparative Example 4]
In Example 2, a polishing pad having a laminated structure was produced in the same manner as in Example 2 except that no hole was formed. The structure of the polishing layer of the obtained polishing pad is shown in Table 1 below.
As a result of evaluating the polishing performance by the above method, as shown in Table 2 below, the polishing rate and the polishing uniformity were inferior, and the number of defects was slightly increased.

[Comparative Example 5]
In Example 3, a polishing pad having a laminated structure was prepared in the same manner as in Example 3 except that the groove width was 0.5 mm, the groove depth was 0.3 mm, and the hole depth was 0.3 mm. did. The structure of the polishing layer of the obtained polishing pad is shown in Table 1 below.
As a result of evaluating the polishing performance by the above-described method, as shown in Table 2 below, the polishing rate and the polishing uniformity were inferior, and the number of defects was increased. Moreover, the change of the polishing rate and polishing uniformity at the time of long-term use was large, and the stability of the polishing performance was insufficient.

According to the present invention, a high polishing rate can be obtained, excellent polishing uniformity and planarization performance, excellent polishing performance such as less scratching, and even if polishing is continued for a long time, the polishing performance changes. Since a small and long-life polishing pad is provided, the polishing pad is particularly useful when chemically insulating an insulating film such as an oxide film or a metal film formed on a semiconductor wafer.

Claims

A polishing pad having at least a polishing layer,
A groove opened on the polishing side surface of the polishing layer, and a hole opened on the polishing side surface of the polishing layer;
The opening area per one of the holes is 0.05 mm 2 or more,
A polishing pad, wherein the depth of the groove, the depth of the hole, and the thickness of the polishing layer satisfy the following formula (1).
(1) Z>X> Y
(In the formula, X represents the depth of the groove, Y represents the depth of the hole, and Z represents the thickness of the polishing layer.)
The polishing pad according to claim 1, wherein the depth of the groove and the depth of the hole satisfy the following formula (2).
(2) XY ≧ 0.1
(In the formula, X represents the depth of the groove, Y represents the depth of the hole, and the unit of length is mm.)
The polishing pad according to claim 1 or 2, wherein the depth of the groove satisfies the following formulas (3) to (5).
(3) X ≧ 0.5
(4) 0.50 × Z ≦ X ≦ 0.90 × Z
(5) ZX ≧ 0.2
(In the formula, X represents the depth of the groove, Z represents the thickness of the polishing layer, and the unit of length is mm.)
The polishing pad according to any one of claims 1 to 3, wherein the depth of the hole satisfies the following formulas (6) to (8).
(6) Y ≧ 0.2
(7) 0.30 × Z ≦ Y ≦ 0.85 × Z
(8) ZY ≧ 0.4
(In the formula, Y represents the depth of the hole, Z represents the thickness of the polishing layer, and the unit of length is mm.)
The polishing pad according to any one of claims 1 to 4, wherein the groove has a lattice shape.
Ratio (a) of the total volume (a) of the grooves opened on the polishing side surface of the polishing layer and the total volume (b) of holes opened on the polishing side surface of the polishing layer and having an opening area of 0.05 mm 2 or more (a) 6. The polishing pad according to claim 1, wherein / b) is in the range of 50/50 to 90/10.
The polishing pad according to any one of claims 1 to 6, wherein a cushion layer is laminated on a surface opposite to the polishing side surface of the polishing layer.
The polishing pad according to any one of claims 1 to 7, wherein the polishing layer has a non-foamed structure.
A semiconductor wafer polishing method using the polishing pad according to any one of claims 1 to 8.
A method of manufacturing a semiconductor device using the polishing pad according to any one of claims 1 to 8.