JP5588528B2 - Polishing pad and manufacturing method thereof - Google Patents

Description

  The present invention relates to a polishing pad and a method for manufacturing the same, and more particularly, to a polishing pad that enables effective slurry collection and transportation and a method for manufacturing the same.

  The chemical mechanical planarization / polishing (CHEMICAL MECHANICAL PLANARIZATION / CHEMICAL MECHANICAL POLISHING, hereinafter referred to as CMP) process is a process introduced for global planarization of semiconductor devices. As the line width is miniaturized and the wiring structure is multilayered, it is attracting attention as a more important process.

  In the CMP process, the polishing rate and the degree of flatness are important, and this is determined by the process conditions of the polishing equipment and the polishing slurry and polishing pad which are consumable members used. In particular, the polishing pad uniformly disperses the polishing slurry supplied in contact with the surface of the wafer on the wafer, and the physical removal action is caused by the polishing particles inside the polishing slurry and the surface protrusions of the polishing pad. To.

  At this time, the polishing pad surface that is in direct contact with the wafer must maintain a state in which the polishing slurry is saturated, and the polishing slurry must flow smoothly. For this purpose, US Pat. No. 5,578,362 discloses a technique for forming fine holes (for example, pores) on the surface of the polishing pad.

  Thus, it is very important to maintain a state where the polishing slurry is saturated in the polishing pad in order to increase the role and performance of the CMP process polishing pad. Therefore, a large slurry flow is generated on the polishing pad. Various grooves (GROOVE) for forming are formed, and in addition to this, fine holes are formed on the surface of the polishing pad by opening a fine porous material as described above.

  By the way, the technology has been developed in the form of trying various patterns in connection with the groove formation, but the porous for technology for forming fine holes restricts the specific fore formation method. The actual situation is limited to use.

  That is, there are advantages and disadvantages according to the conventional fore forming method, but in actual CMP process, the process is adjusted in consideration of such advantages and disadvantages.

  However, the demand for further fineness and sophistication in the semiconductor process increases the demand for a technology for producing a porous fore that is further advanced by one step to support the CMP process.

  The present invention has been devised to meet the above-described conventional demands, and its purpose is polishing capable of maximizing polishing performance and planarization performance by collecting and using polishing slurry during the CMP process. A pad and a method for manufacturing the same are provided.

  In order to achieve the above object, a polishing pad that performs a polishing process by moving in contact with the surface of an object to be polished according to the present invention, the polishing pad includes a polishing layer, and the polishing layer includes: The polishing layer comprises two or more kinds of porous fores, each of which is controlled in size by at least two of an inert gas, a capsule-type foaming agent, a chemical foaming agent and a liquid microelement. On the surface, pores due to the opening of the two or more kinds of porous fores are distributed.

  In order to achieve the above-described object, a polishing pad manufacturing method according to the present invention includes a step of mixing a material for forming a polishing layer, and an inert gas capable of controlling foresize in the mixture in the step, and a capsule type foam. Mixing at least two of the agent, the chemical foaming agent and the liquid microelement to form two or more kinds of porous fore, and gelling and curing the mixture formed through the step, Producing a polishing layer containing two or more types of porous fores; and processing the polishing layer to distribute pores due to the opening of the two or more types of porous fores on the surface. Made.

  According to the present invention, by controlling a multiple (double) fore which is not a single fore, it is possible to realize an improved CMP polishing performance by enabling efficient slurry collection and transfer. This makes it possible to achieve the fineness of the CMP process required by miniaturization of the semiconductor process.

1 is a cross-sectional view of a polishing pad according to an embodiment of the present invention. FIG. 2 is an enlarged image of a cross section of the polishing pad polishing layer of FIG. 1. FIG. 2 is a schematic view of a polishing apparatus equipped with the polishing pad of FIG. 1. 3 is a flowchart of a polishing layer manufacturing process of a polishing pad according to an embodiment of the present invention. 3 is a surface pore image of a polishing layer including a fore by an inert gas and a fore by a liquid microelement according to an embodiment of the present invention. Similarly, it is a surface pore image of a polishing layer including a fore made of an inert gas and a fore made of a liquid microelement according to an embodiment of the present invention. 6 is a view showing the polishing efficiency of a polishing pad formed by a method according to the present invention (Example 2 and Example 3) in comparison with a conventional method.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view of a polishing pad according to an embodiment of the present invention.

  As shown in the drawing, a polishing pad 100 according to an embodiment of the present invention includes a support layer 110 and a polishing layer 120. The support layer 110 is a part that allows the polishing pad 100 to adhere to the platen 3 as shown in FIG. 3. The support layer 110 is made of a material having resilience corresponding to the force of pressing the silicon wafer 7 to be polished loaded on the head 5 facing the platen 3, and the polishing formed thereon The layer 120 supports the silicon wafer 7 with a uniform elastic force. Therefore, the hardness is lower than that of the polishing layer 120 which is mainly made of a non-porous solid uniform elastic material and is formed thereon.

  Further, the support layer 110 is at least partially transparent or translucent and can transmit a light beam 170 used for detecting the flatness of the surface to be polished. In FIG. 3, the wafer 7 on which a film to be polished such as a metal or an insulating layer is illustrated as an object to be polished, but various substrates such as a substrate on which a TFT-LCD is formed, a glass substrate, a ceramic substrate, a polymer plastic substrate, etc. Of course, can be used for the object to be polished. In some cases, the polishing pad 100 can be configured without the support layer 110.

  Further, FIG. 3 shows a case where the pattern of the polishing pad 100 is circular so as to be suitable for the rotary polishing apparatus 1, but depending on the form of the polishing apparatus 1, deformation may be made in various forms such as a square and a regular square. Of course, it is possible.

  The polishing layer 120 is a part that directly contacts the wafer 7 to be polished as shown in FIG. The polishing layer 120 can be formed by mixing a predetermined polishing layer forming material or chemical bonding. That is, the polymer matrix 130 forming the polishing layer 120 is made of various known components, but the description of the known materials and forming substances is omitted.

  Such a polishing layer 120 may include two or more types of porous fores, such as two or more types of porous fores, including an inert gas, a capsule type foaming agent, a chemical foaming agent, and the like. This corresponds to at least two liquid microelements that have been subjected to foresize control.

  In other words, the types of porous fore can be distinguished from each other by the method of forming the porous fore, but the fore produced by the inert gas, the fore produced by the capsule-type blowing agent, the chemical At least two types of fores produced by the foaming agent and fores produced by the liquid microelements are included in the polishing layer 120 according to the present invention.

  Here, each type of fore may be formed so as to be distinguished from each other in size, but the present invention is not limited to this.

  Hereinafter, as an example of the present invention, it is assumed that the polishing layer 120 is formed with two types of porous fores, that is, a first porous fore and a second porous fore. It is assumed that the fore is formed by a liquid microelement and the second porous fore is formed by an inert gas.

  In this way, when the first porous fore by the liquid microelement is included in the polishing layer, the material generated by mixing the polishing layer forming material mentioned above is, for example, a hydrophilic polymer matrix containing polyalkylene glycol (Hereinafter referred to as “polyalkylene glycol-containing hydrophilic polymer matrix”) 130.

  That is, the polishing layer occupies a certain area in the polyalkylene glycol-containing hydrophilic polymer matrix 130 and is uniformly distributed, that is, embedded liquid microelements (hereinafter referred to as “embedded”). And a second porous fore 142 that is a gas phase fore including an inert gas embedded therein.

  The actual examples of the first porous fore (liquid microelement fore) 141 and the second porous fore (gas phase fore) 142 included in the polishing layer are as shown in FIG.

  A plurality of fine pores 141 ′ and 142 ′ defined and opened by the first porous fore 141 and the second porous fore 142 are uniformly arranged on the surface 160 of the polishing layer in direct contact with the wafer 7. ing.

  Here, the meaning that the pores 141 ′ and 142 ′ are defined and opened by the respective porous fores 141 and 142 means that liquid microelements or inert gas embedded in the polishing layer 120 are leaked to the outside. This means that the region containing the liquid microelement or the inert gas remains as the pore 141 ′, and the predetermined substances can be captured from the outside.

  The porous fores 141 and 142 embedded by the polishing pad 100 being worn during the polishing process are continuously exposed to the polishing layer surface 160 to form pores 141 ′ and 142 ′. This is replaced by the polishing slurry 13. Therefore, since only the polymer matrix is present on the polishing surface 160, the polishing pad 100 is not unevenly worn, and the silicon wafer 7 to be polished can be sharpened uniformly.

  The polyalkylene glycol-containing hydrophilic polymer matrix 130 is preferably formed of a material that is insoluble in the polishing slurry 13 that is a chemical solution for planarization. For example, as shown in FIG. 3, the polishing slurry 13 supplied through the nozzle 11 of the polishing apparatus 1 is formed of a material that cannot penetrate.

  The polyalkylene glycol-containing hydrophilic polymer matrix 130 can be formed by chemical bonding or physical mixing between the polymer matrix forming material, the hydrophilic material, and the polyalkylene glycol compound.

  Here, the material of the polymer matrix produced by the polymer matrix forming substance is polyurethane, polyether, polyester, polysulfone, polyacryl, polycarbonate, polyethylene, polymethyl methacrylate, polyvinyl acetate, polyvinyl chloride, polyethyleneimine, polyethersulfone, It may correspond to any one selected from the group made of polyetherimide, polyketone, melamine, nylon and fluorinated hydrocarbon, or a mixture thereof.

  The polyalkylene glycol-containing hydrophilic polymer matrix 130 corresponds to such a polymer matrix in which a hydrophilic substance and a polyalkylene glycol compound are bonded by a chemical method or mixed by a physical method.

  Examples of hydrophilic substances include polyethylene glycol, polyethylene propylene glycol, polyoxyethylene alkylphenol ether, polyoxyethylene alkyl ether, polyethylene glycol fatty acid ester, polyoxyethylene alkylamine ether, glycerin fatty acid ester, sugar fatty acid ester, and sorbitol fatty acid ester. Any one selected from these groups or a mixture thereof can be cited as an example.

  The polyalkylene glycol compound may be any one selected from the group consisting of a compound in which alkylene oxide is added to a compound containing water or active hydrogen, or a mixture thereof.

  Of course, the polishing layer forming material as described above may include various materials other than those described above.

  The embedded liquid microelements forming the first porous fore 141 are formed of a liquid material that is not compatible with the polyalkylene glycol-containing hydrophilic polymer matrix 130, but the aliphatic mineral oil, the aromatic mineral oil, and the molecular end. Any one selected from the group consisting of silicone oil having no hydroxyl group, soybean oil, coconut oil, palm oil, cotton oil, coconut oil, hydrogenated oil, or a mixture thereof may be used.

  The first porous fore 141 made of embedded liquid microelements is preferably formed in a fine spherical shape dispersed in the polyalkylene glycol-containing hydrophilic polymer matrix 130. The average spherical diameter is preferably 1 to 30 μm, and more preferably 2 to 10 μm. When the spherical diameter is within the above range, it is most suitable for collecting and supplying the polishing slurry 13. However, a suitable spherical diameter can be changed according to the type of polishing slurry 13 used, and the size of the embedded liquid microelement 141 can be changed accordingly.

  The form of the first porous fore 141 by the embedded liquid microelement, that is, the average diameter and the concentration of the sphere, can be easily and variously adjusted by changing the hydrophilicity of the polyalkylene glycol-containing hydrophilic polymer matrix 130. Can do.

  The form of the first porous fore 141 by the embedded liquid microelement can be easily and variously adjusted according to the weight ratio of the liquid substance. Preferably, the polymer matrix-forming material, for example, 20 to 50% by weight, more preferably 30 to 40% by weight, based on the total weight of the polyurethane substrate, is mixed with the liquid material, depending on the desired form of microelements. A first porous fore 141 can be generated.

  The size and concentration of the first porous fore 141 and the pores 141 ′ defined by the embedded liquid microelements depend on the hydrophilicity of the polyalkylene glycol-containing hydrophilic polymer matrix 130 and / or the amount of the liquid material. Since various adjustments are possible, there is an advantage that the polishing pad 100 having various polishing performances can be manufactured according to the type of the object to be polished and / or the type of the polishing slurry 13.

  On the other hand, the second porous fore 142 is formed by injection of an inert gas, a capsule-type foaming agent, a chemical foaming agent, or the like.

  Here, the inert gas can mean a chemically stable gas because the valence is “0”, but helium (He), neon (Ne), argon (Ar), krypton (Kr), Zenon (Xe), radon (Rn), etc. are contained in such an inert gas. Furthermore, the inert gas corresponds to any gas that does not react with the polymer matrix, such as N2, other than the group 8 element in the periodic table, for example, does not participate in the urethane reaction.

  The foaming agent can be roughly classified into a chemical foaming agent and a physical foaming agent as a foaming agent that is mixed with a predetermined raw material and generates a large amount of bubbles by heat vaporization or reaction.

  The chemical blowing agent foams with carbon dioxide generated by reaction with water using the activity of isocyanate groups, so water is used as the blowing agent, and the physical blowing agent is mixed with gas, or By generating heat of reaction using a decomposable or evaporating foaming agent, it does not participate in the polymer reaction to form bubbles. Since the kind and characteristic of such a foaming agent are only what was already known, more detailed description is abbreviate | omitted.

  The second porous fore 142 is formed in the polishing layer by mixing an inert gas and various foaming agents (capsule type foaming agent and chemical foaming agent), and is larger than the first porous fore 141. Preferably, the second porous fore 142 is formed to have a volume that is 10 times or more that of the first porous fore 141.

  Hereinafter, a process of manufacturing the polishing layer 120 of the polishing pad 100 according to an embodiment of the present invention will be described with reference to FIG.

  First, materials for forming the polishing layer 120 are mixed (S100). Specifically, the previously described materials for forming the polyalkylene glycol-containing hydrophilic polymer matrix 130 can be mixed with each other (step S100).

  Here, the polyalkylene glycol-containing hydrophilic polymer matrix 130 forming substance is a substance produced by mixing or reacting a hydrophilic substance and a polyalkylene glycol compound with the polymer matrix forming substance. This preferably proceeds by a stirring method.

  In the mixing process, liquid substances such as mineral oil can be mixed together, and at this time, an inert gas such as argon (or a specific foaming agent that replaces this) can be administered and mixed together.

  The amount of the liquid substance and the inert gas to be mixed here can be adjusted as much as necessary depending on the size of the type-specific fore to be generated.

  In succession, gelation and curing reaction proceed (S110). That is, the mixture is injected into a mold having a predetermined shape and solidified through gelation and curing processes. At this time, the gelation reaction may proceed at 80 to 90 degrees for 5 to 30 minutes, and the curing reaction may proceed at 80 to 120 degrees for 20 to 24 hours. Of course, the time can be varied in various ways to find the optimum condition.

  Finally, the resultant cured in a predetermined shape is processed (S120). Processing includes demolding, cutting, surface processing, and cleaning processes. First, the cured reaction product is removed from the mold and cut to have a predetermined thickness, pattern, and shape. Of course, the polishing layer 120 can be formed in a sheet shape by any method known in the art of the polymer sheet manufacturing field, such as casting and extrusion molding, in order to improve productivity. In addition, it is desirable to form various types of grooves on the surface of the polishing layer 120 so that the polishing slurry 13 can be uniformly supplied to the working surface of the polishing layer 120.

  Thereafter, the polishing layer 120 is completed through a cleaning process. During the cleaning process, the liquid microelements 141 on the polishing layer surface 160 are spouted, and the open pores 141 ′ are distributed on the polishing layer surface 160. At this time, it is preferable that the cleaning process is performed using a cleaning liquid that prevents the liquid microelement 141 that has spouted from remaining on the surface 160 of the polishing layer.

  The polishing pad 100 can be completed with the polishing layer 120 alone, but if necessary, the support layer 110 is manufactured by a method widely known in the manufacturing process field of the polishing pad 100 and the support layer 110 and the polishing layer 120 are bonded. Thus, the polishing pad 100 can be completed.

More detailed contents regarding the present invention will be explained through comparison of the following specific experimental examples, and contents not described here can be sufficiently technically analogized by those skilled in the art. Therefore, explanation is omitted. Of course, the scope of the present invention is not limited by the following experimental examples.
<Experimental example 1>
A 200 kg reactor was charged with 50 kg of polytetramethylene glycol (molecular weight 1000), 50 kg of polyethylene glycol (molecular weight 1000) and 52 kg of toluene diisocyanate, and reacted at a temperature of 70 to 80 ° C. for 4 to 5 hours. Was 11.0%. The viscosity of the isocyanate prepolymer produced thereby was 6,900 cPs (25 ° C.).
<Experimental example 2>
Using a casting machine, 100 kg of the isocyanate prepolymer of Experimental Example 1, mineral oil (hereinafter KF-70) (SEOJIN Chemical Manufacturing) 46 kg, and 33 kg of MOCA were discharged through a mixing head of 5000 rpm. Give me. At this time, Ar gas, which is an inert gas, is administered by Mixing Head at a volume ratio of 10%.

  After this, the mixture is poured straight into a square mold. The injected reaction solution is gelled for 30 minutes and then cured in an oven at 100 ° C. for 20 hours.

  The produced cured product was taken out with a mold and the surface was cut to produce a polishing layer of a polishing pad.

  The surface fore image of such a polishing layer is shown in FIG.

The polishing performance and flattening performance of the manufactured pad are shown in FIG. 7 (the polishing pad according to this example is “Hybrid Fore 1”).
<Experimental example 3>
Using Casting Machine, 100 kg of the isocyanate prepolymer of Experimental Example 1, 46 kg of mineral oil (hereinafter KF-70) (Sojin Chemical Manufacturing) and 33 kg of MOCA are discharged through a mixing head at 5000 rpm. At this time, Ar gas which is an inert gas is administered by Mixing Head at a volume ratio of 20%.

  After this, the mixture is poured straight into a square mold. The injected reaction solution is gelled for 30 minutes and then cured in a 100 ° C. oven for 20 hours.

  The produced cured product was taken out from the mold and the surface was cut to produce a polishing layer of the polishing pad.

  The surface fore image of such a polishing layer is shown in FIG.

  The polishing performance and planarization performance of the manufactured pad are shown in FIG. 7 (the polishing pad according to this example is “Hybrid Fore 2”). In the drawings, the “solid-phase capsule fore” does not use different types of composite fore (ie, the first porous fore and the second porous fore) as in the present invention, but a single solid foreground. This shows a case of a polishing pad using only a phase capsule fore (here, a solid phase capsule can mean a fine powder having an empty interior), and a “liquid microelement fore” is also used in the present invention. In other words, the composite fore (ie, the first porous fore and the second porous fore) different from each other is not used, but the case of a polishing pad including only a single liquid microelement is shown. .

  When using composite fore having different sizes as described above, the first porous fore having a relatively small size enables precise polishing by collecting a small amount of polishing slurry particles. The relatively large second porous fore collects a large amount of polishing slurry particles at a time so that a high polishing rate can be processed.

  In this way, by allowing different types of fore to be included in the polishing layer of the polishing pad at the same time, a more sophisticated polishing operation can be performed.

  In the above-described embodiment, it has been mainly explained that two types of porous fores are formed. However, as described above, the present invention is not limited to this.

  That is, the polishing pad according to the present invention includes a fore formed by a liquid microelement, a fore formed by a solid-phase capsule, a fore formed by injecting an inert gas, and a fore formed by a chemical foaming agent. More than three types can also be included. At this time, the size of the generated porous fore for each type may be as described above, and may be changed depending on the type of the fore forming material or to increase the polishing efficiency. Of course, it can also be done.

  In particular, each fore forming method can control the fore size depending on the concentration of the mixed substance, the reaction temperature, etc., but each type of fore is not necessarily required to have a different size.

  On the other hand, the present invention is not limited to the specific embodiments described above, and can be implemented with various modifications and corrections without departing from the spirit of the present invention.

  As described above, according to the present invention, by controlling a multiple (double) fore that is not a single fore, it is possible to efficiently collect and transfer slurry, and to improve CMP polishing performance. It can be implemented. This makes it possible to achieve the fineness of the CMP process required by miniaturization of the semiconductor process.

3 Platen 5 Head 100 Polishing Pad 110 Support Layer 120 Polishing Layer

Claims (7)

(a) mixing a polishing layer forming material;
(b) Mixing at least two of inert gas, capsule-type foaming agent, chemical foaming agent and liquid microelement, each of which is capable of controlling foresize in the mixture of step (a). Forming a porous fore of
(c) gelling and curing the mixture produced through the step (b) to produce a polishing layer containing the two or more types of porous fore;
(d) viewing including the the steps of distributing the pores et al opening of the two or more porous fore on the surface by processing the abrasive layer,
The diameter of the porous fore of the first type is greater than 2 μm and less than 10 μm;
The volume of the second type of porous fore is not less than 10 times the volume of the first type of porous fore,
A method for producing a polishing pad, comprising: In the step (b), at least the inert gas is mixed with the mixture of the step (a).
The method for manufacturing a polishing pad according to claim 1, wherein the inert gas is selected from a group 8 element of the periodic table and a gas that does not react with the polishing layer forming substance. In the step (b), at least the liquid microelement is mixed in the mixture of the step (a).
The liquid material constituting the liquid microelement is selected from the group consisting of aliphatic mineral oil, aromatic mineral oil, silicon oil having no hydroxyl group at the molecular end, soybean oil, coconut oil, palm oil, cotton oil, coconut oil and hydrogenated oil. The method for manufacturing a polishing pad according to claim 1, wherein the polishing pad is any one of them or a mixture thereof. In the polishing pad that performs the polishing process by moving in contact with the surface of the object to be polished, the polishing pad includes a polishing layer,
The polishing layer includes two or more kinds of porous fores, each of which is controlled in size by at least two of an inert gas, a capsule-type foaming agent, a chemical foaming agent and a liquid microelement.
The surface of the polishing layer is distributed with pores due to the opening of the two or more types of porous fore ,
The diameter of the porous fore of the first type is greater than 2 μm and less than 10 μm;
The volume of the second type of porous fore is not less than 10 times the volume of the first type of porous fore,
A polishing pad characterized by that. The polishing layer contains at least the inert gas,
The polishing pad according to claim 4, wherein the inert gas is selected from a group 8 element of the periodic table and a gas that does not react with the polishing layer forming material. The polishing layer includes at least the liquid microelement,
The liquid material constituting the liquid microelement is selected from the group consisting of aliphatic mineral oil, aromatic mineral oil, silicon oil having no hydroxyl group at the molecular end, soybean oil, coconut oil, palm oil, cotton oil, coconut oil and hydrogenated oil. The polishing pad according to claim 4, wherein the polishing pad is any one of these or a mixture thereof.   The polishing layer has a first porous fore made of the liquid microelement, a size larger than that of the first porous fore, injection of the inert gas, injection of the capsule-type foaming agent, and chemical foaming. The polishing pad according to claim 4, further comprising a second porous fore formed by at least one of the injections of the agent.