JP4456691B2 - Conditioner manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a conditioner. More specifically, the present invention can easily adjust the protruding amount of abrasive grains, and the tips of the abrasive grains are all facing outward, and polishing for chemical mechanical polishing such as interlayer insulating films of semiconductor devices, metal wirings, etc. The present invention relates to a method for manufacturing a conditioner having excellent conditioning efficiency, in which there is no possibility that the polishing pad is contaminated with metal during conditioning of the pad, and there is no possibility of damaging the wafer surface due to falling off of abrasive grains.
[0002]
[Prior art]
Multilayer interconnects are becoming increasingly important for high integration and high speed of VLSI, and there is a demand for further advancement in the flattening process of interlayer insulating films and metal interconnects that form the core of this technology. In general, in a wafer processing apparatus for polishing the surface of a semiconductor wafer, a polishing pad is attached to a disk-shaped surface plate, one or more wafers are placed on the upper surface of the surface plate, and these wafers are placed on the polishing pad. Chemical mechanical polishing (CMP) is performed by chemical and mechanical action of an interface by supplying a polishing liquid containing fine abrasive particles between a polishing pad and a wafer while forcibly rotating by a carrier.
As a polishing pad, a velor type pad in which a polyester nonwoven fabric is impregnated with polyurethane resin, a suede type pad in which a polyester nonwoven fabric is used as a base material and a foamed polyurethane layer is formed thereon, or a foamed polyurethane pad having closed cells is used. Has been. Also, as the abrasive particles, ferrite powder, alumina powder, barium carbonate, colloidal silica, cerium oxide, etc. are used, and as the polishing liquid, potassium hydroxide solution, dilute hydrochloric acid, dilute nitric acid, hydrogen peroxide solution, iron nitrate solution etc. are used. used. While such wafer polishing is repeated, chips or abrasive particles of the work material enter the fine holes of the polishing pad, causing clogging, or the surface of the polishing pad due to the chemical reaction heat between the abrasive particles and the wafer. Becomes a mirror surface, and the polishing rate decreases. For this reason, it is necessary to condition the polishing pad constantly or periodically.
However, in the conditioner with the abrasive grains fixed by the conventional electrodeposition method, the abrasive grains are not completely one layer, and there are always abrasive grains sandwiched between the abrasive grains, which fall off and are polished. There was a problem of remaining on the pad and damaging the wafer surface. In conditioners with metal grains fixed by metal bonds, copper and the like are eluted by highly reactive polishing liquids, and nickel and the like remain in the polishing pad. However, since it adheres on the wafer which is a workpiece, the cleaning process of the wafer after chemical mechanical polishing is very troublesome. Furthermore, in both the electrodeposition type and the metal bond type, it is very difficult to adjust the protruding amount of diamond abrasive grains, and there is a problem that it takes a long processing time to set the protruding amount of diamond abrasive grains to a desired value. .
Various methods have been taken to prevent the abrasive grains from falling from the conditioner and the elution of metal. For example, in Japanese Patent Laid-Open No. 2-225825, an abrasive layer is formed by temporarily fixing a single abrasive grain on the inner surface of an inversion type by electrodeposition, and embedding and fixing the temporarily fixed abrasive with metal or resin. In addition, a conditioner that is manufactured by joining a base metal to the abrasive layer and removing the reversal mold, where the most protruding parts of the abrasive grains are all on the same plane, has been proposed. ing. In Japanese Patent Laid-Open No. 10-15819, a single layer of abrasive grains is temporarily fixed to a base metal by plating, the floating stones of the temporarily fixed abrasive grains are removed with a grinding stone, and plating is performed until the abrasive grains are embedded. There has been proposed a conditioner in which the most protruding portion is exposed so that the protruding amount of the abrasive grains is 5 to 30% of the average particle diameter by performing the quarrying process, and there is no fear of dropping off the abrasive grains. Japanese Patent Laid-Open No. 10-249708 discloses that an abrasive grain is fixed to a base metal from a brazing material to form an abrasive grain layer, and then the abrasive grain layer is covered with a synthetic resin layer so that no metal is exposed on the surface. In addition, there has been proposed a conditioner that does not cause the abrasive grains to fall off and the metal to elute. Furthermore, JP-A-11-33911 discloses that an abrasive grain is fixed to a base metal by plating to form an abrasive grain layer, and the abrasive grain layer is covered with a synthetic resin layer, and then the surface portion of the synthetic resin layer is removed. Then, a conditioner has been proposed in which the tip of the abrasive grains protrudes from the synthetic resin layer and the plated metal is not exposed by being covered with the synthetic resin layer, and there is no risk of abrasive grains falling off and metal elution. .
However, all of these conditioners are inevitably costly due to the long manufacturing process, and even if they are covered with a synthetic resin layer, as long as a metal material is used, the conditioner is completely free from metal elution. Anxiety could not be wiped out. Furthermore, even if the quarrying process is performed, the tip of the abrasive grain effective for conditioning does not always face outward, and therefore, lapping may be required in some cases. For this reason, there has been a demand for a conditioner that has no fear of falling off of abrasive grains and elution of metal, is excellent in conditioning efficiency, and can be manufactured easily and easily.
[0003]
[Problems to be solved by the invention]
The present invention makes it possible to easily adjust the protruding amount of abrasive grains, and the tips of the abrasive grains are all directed outward, and during conditioning of polishing pads for chemical mechanical polishing such as interlayer insulating films of semiconductor devices and metal wirings. An object of the present invention is to provide a method for manufacturing a conditioner having excellent conditioning efficiency, in which there is no possibility that the polishing pad will be contaminated with metal and there is no possibility that the surface of the wafer will be damaged due to removal of abrasive grains.
[0004]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have provided a hole for fitting abrasive grains in the mother die and a gas passage communicating with the hole. The grains are fitted with the tips facing the gas passage, and in this state, it is found that a conditioner with the tips all facing outwards can be produced by fixing the abrasive grains with a binder. The present invention has been completed based on the findings.
That is, the present invention
(1) Abrasive grains are fitted in a hole having a gas passage communicating with the outside of the mother die by reducing the gas passage, and the metal die , ceramic powder or A conditioner manufacturing method characterized by forming a grain layer by adhering abrasive grains by filling and sintering a binder made of synthetic resin ,
(2) The method for producing a conditioner according to item (1), wherein the depth of the hole is 10 to 50% of the average grain size of the abrasive grains, and
(3) The method for producing a conditioner according to item (1), wherein the binder is a synthetic resin;
Is to provide.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The conditioner manufacturing method of the present invention is provided on the surface of the mother die, and in the hole having the gas passage communicating with the outside of the mother die, the abrasive is fitted into the mother die by reducing the pressure of the gas passage. By filling and sintering the binder, the abrasive grains are fixed to form an abrasive grain layer. Fig.1 (a) is a top view of one aspect | mode of the mother die used for this invention method, FIG.1 (b) is the perspective view. In the mother die of this aspect, the abrasive grain layer cavity 2 is provided in the annular portion surrounded by two concentric circles at the peripheral edge of the mother die 1, and the abrasive grain layer cavity is divided into six parts in a discontinuous manner. ing. At the bottom of the abrasive layer cavity, holes 3 for fitting the abrasive grains are provided, and gas passages communicating from the respective holes to the back surface of the mother die are provided. The gas passage is composed of a narrow passage that is connected to the hole and has a diameter smaller than the grain size of the abrasive grains, and a thick passage that opens on the back surface of the mother die. The depth of the hole is preferably 10 to 50% of the average particle diameter of the abrasive grains, and more preferably 15 to 35%. Since the protruding amount of the abrasive grains of the conditioner of the present invention is substantially equal to the depth of the hole, the protruding amount of the abrasive grains of the conditioner can be made uniform by making the hole depth constant. When the depth of the hole is less than 10% of the average grain size of the abrasive grains, the protruding amount of the abrasive grains is small, and the conditioning efficiency may be reduced. If the depth of the hole exceeds 50% of the average grain size of the abrasive grains, the holding power of the abrasive grains becomes small, and the abrasive grains may fall off during conditioning. There is no restriction | limiting in particular in the shape of a hole, For example, it can be set as the shape used as a part of spherical surface, the shape of a cone, a polygonal pyramid, the shape which also serves as the chamfering of a gas passage. In the method of the present invention, the material of the mother die is not particularly limited, and for example, a graphite die, a die or the like can be used.
[0006]
FIG.2 and FIG.3 is explanatory drawing of the one aspect | mode of the manufacturing method of the conditioner of this invention. This figure is a partial cross-sectional view taken along a plane parallel to the central axis through four holes provided on the surface of the mother die. As shown in FIG. 2 (a), holes 3 for fitting abrasive grains are provided in the abrasive layer cavities 2 on the surface of the mother die 1, and gas passages communicating with the back surface of the mother die from the respective holes. 4 is provided. The gas passage is composed of a narrow passage that is connected to the hole and has a diameter smaller than the grain size of the abrasive grains, and a thick passage that opens on the back surface of the mother die. As shown in FIG. 2B, the abrasive grains 5 are loaded in the abrasive grain layer cavity, and the gas passage 4 is depressurized by deaeration from the back side of the mother die. By reducing the pressure of the gas passages, the abrasive grains are drawn into the respective holes, and the abrasive grains are fitted into the holes with their tips directed toward the gas passages. Although there is no restriction | limiting in particular in the grade of pressure reduction, It is preferable that it is 1-70 kPa of pressure, and it is more preferable that it is 5-50 kPa. When the pressure is less than 1 kPa, the abrasive grains are excessively drawn into the hole and the gas passage, and there is a possibility of biting into the mother die. When the pressure exceeds 70 kPa, the force for drawing the abrasive grains into the hole is weak, and the tip of the abrasive grains may not be directed to the gas passage. FIG. 2 (c) shows the state shown in FIG. 2 (c) after reducing the pressure of the gas passage and fitting the abrasive grains into the hole with the tip facing the gas passage. And There is no particular limitation on the method for removing the excess abrasive grains, for example, it is possible to drop the excess abrasive grains by inverting the master mold while the gas passage is kept under reduced pressure. The excess abrasive grains can be sucked up with a weak vacuum, or the excess abrasive grains can be picked up from the abrasive layer cavity. In the method of the present invention, instead of placing abrasive grains in the abrasive layer cavity as shown in FIG. 2 (b), one abrasive grain is placed in each hole and the gas passage is decompressed to reduce the abrasive grains. The tip can be directed to the gas passage, and the state shown in FIG.
[0007]
In the method of the present invention, after the abrasive grains are fitted in the holes provided on the surface of the mother die with the tips facing the gas passages, the mother die is filled with a binder and sintered to fix the abrasive particles. To do. In the embodiment shown in FIG. 3 (a), the space formed by fitting the cylindrical outer mold 6 is filled with the binder 7 and pressed using the push punch 8. By heating while pressing, the binder is sintered, and the abrasive grains 5 are fixed to the substrate 9 formed of the binder as shown in FIG. There is no restriction | limiting in particular in the binder to be used, For example, metal powder, ceramic powder, a synthetic resin etc. can be mentioned. In sintering, conditions such as temperature, pressure, and time can be appropriately selected according to the binder to be used. Among the binders, a synthetic resin can be preferably used, and a thermosetting resin can be particularly preferably used. Since the synthetic resin has a low temperature and pressure for sintering, there is little risk of distortion in the shape, and there is no possibility of metal elution during conditioning. Examples of the thermosetting resin to be used include urea resin, melamine resin, phenol resin, epoxy resin, diallyl phthalate resin, polyester resin, and polyimide resin. Among these, a phenol resin can be suitably used.
[0008]
There is no restriction | limiting in particular in the abrasive grain used for this invention method, For example, a diamond, CBN, a cerium oxide, a sapphire, a ruby, a garnet, a silicon carbide, an alumina etc. can be mentioned. When the conditioner is used for conditioning a polishing pad for chemical mechanical polishing, it is preferable to use diamond abrasive grains. The grain size of the diamond abrasive grains is preferably # 35 to # 120, and more preferably # 50 to # 100. When the grain size of the diamond abrasive grains becomes coarser than # 35, natural diamond is required and it becomes very expensive. If the grain size of the diamond abrasive grains is finer than # 120, it may be difficult to work the hole and the gas passage.
As shown in FIG. 3B, the binder is sintered to form the substrate 9, and after the conditioner to which the abrasive grains 5 are fixed is formed, the mother mold is slowly cooled together with the conditioner, and the mother mold Remove and remove the conditioner. FIG. 4A is a plan view of a conditioner manufactured using the matrix shown in FIG. 1, and FIG. 4B is a perspective view thereof. In the conditioner manufactured by the method of the present invention, as shown in FIG. 3 (c), the tips of the abrasive grains are all directed outward, and the protruding amounts of the abrasive grains are all constant. Therefore, the conditioner manufactured by the method of the present invention does not need to be stoned or lapped. When the conditioner manufactured by the method of the present invention is used for conditioning a polishing pad in chemical mechanical polishing, conditioning can be efficiently performed in a short time, and the surface roughness of the conditioned polishing pad is fine and flat. Excellent in properties.
[0009]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
Example 1
A conditioner was manufactured using a graphite mold having the shape shown in FIG.
The graphite mold has a diameter of 100 mm and has an annular abrasive grain layer cavity of 10 mm width at the outer peripheral edge, and diamond abrasive grains are fitted into each of the divided abrasive layer cavities. There are 27 holes each. In addition, a gas passage composed of a narrow passage having a diameter of 100 μm and a thick passage having a diameter of 1 mm is provided from each hole to the back surface of the graphite mold.
Place diamond abrasive grains of grain size # 60 in the graphite type abrasive layer cavity, apply 20 kPa of reduced pressure to the back of the graphite mold, and insert the diamond abrasive grains into the holes. Removed.
The graphite mold was fitted with a cylindrical graphite outer mold having an inner diameter of 100 mm, an outer diameter of 140 mm, and a height of 30 mm, and preheated to 100 ° C. The mother mold was filled with 70 g of a phenol resin, and a pressure of 100 kg / cm ² was applied from above by a punch, and the temperature was raised to 170 ° C. and heated for 10 minutes to cure the phenol resin. Next, after gradually cooling to room temperature, the press punch, outer mold and graphite mold were removed to obtain a conditioner.
When the diamond abrasive grains of the conditioner were observed using a scanning electron microscope, the tips of the abrasive grains were all directed outwardly perpendicular to the abrasive layer surface, and the amount of protrusion was uniform.
[0010]
【The invention's effect】
In the conditioner manufactured by the method of the present invention, the tips of the abrasive grains are all directed outward, and the protruding amount of the abrasive grains is all constant. Therefore, the conditioner manufactured by the method of the present invention does not need to be stoned or lapped. When the conditioner manufactured by the method of the present invention is used for conditioning a polishing pad in chemical mechanical polishing, conditioning can be efficiently performed in a short time, and the surface roughness of the conditioned polishing pad is fine and flat. Excellent in properties.
[Brief description of the drawings]
FIG. 1 is a plan view and a perspective view of an embodiment of a mother die used in the method of the present invention.
FIG. 2 is an explanatory view of an embodiment of a method for producing a conditioner of the present invention.
FIG. 3 is an explanatory diagram of an embodiment of a method for producing a conditioner according to the present invention.
4 is a plan view and a perspective view of a conditioner manufactured using the matrix of FIG. 1. FIG.
[Explanation of symbols]
1 Master 2 Abrasive Layer Cavity 3 Hole 4 Gas Passage 5 Abrasive Grain 6 Outer Mold 7 Binder 8 Push Punch 9 Substrate

Claims (3)

Abrasive grains are fitted into a hole provided on the surface of the mother die and having a gas passage communicating with the outside of the mother die by depressurizing the gas passage, and the mother die is made of metal powder, ceramic powder or synthetic resin. by sintering by filling comprising binders, conditioners manufacturing method characterized by forming the abrasive grain layer by fixing the abrasive grains.   The method for producing a conditioner according to claim 1, wherein the depth of the hole is 10 to 50% of the average grain size of the abrasive grains.   The method for producing a conditioner according to claim 1, wherein the binder is a synthetic resin.

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