Manufacturing method for polishing pads and polished products

Abstract

To provide a polishing pad that is low in slurry dependence of a selection ratio and can be used for high-precision torque endpoint detection, and a method for manufacturing a polished product using the same.SOLUTION: A polishing pad comprises a polishing layer that contains a water-soluble organic compound having a carboxylic acid group and / or a sulfonic acid group.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a polishing pad and a method for manufacturing a polished workpiece.

Background Art

[0002] In the semiconductor manufacturing process, chemical mechanical polishing (CMP) is used in the planarization after insulating film formation and the formation process of metal wiring. One of the important technologies required for chemical mechanical polishing is polishing endpoint detection for detecting whether the polishing process is completed. For example, over-polishing or under-polishing with respect to the target polishing endpoint directly leads to product defects. Therefore, in chemical mechanical polishing, it is necessary to strictly control the polishing amount by polishing endpoint detection.

[0003] Chemical mechanical polishing is a complex process, and the polishing rate (polishing rate) changes due to the influence of the operating state of the polishing apparatus, the quality of consumables (slurry, polishing pad, dresser, etc.), and the variation in the state over time during the polishing process. Furthermore, in recent years, the accuracy and in-plane uniformity of the remaining film thickness required in the semiconductor manufacturing process have become increasingly strict. Under such circumstances, it has become more difficult to detect the polishing endpoint with sufficient accuracy.

[0004] As the main methods for polishing endpoint detection, an optical endpoint detection method, a torque endpoint detection method, an eddy current endpoint detection method, etc. are known.

[0005] In the optical endpoint detection method, the wafer is irradiated with light through a transparent window member provided on the polishing pad, and the reflected light is monitored to detect the endpoint. However, slurry may leak from around the window member during polishing, which may reduce the detection accuracy. In addition, since it is necessary to provide window members having different materials and physical properties on the polishing pad, there are problems such as non-uniform polishing in the portion where the window member is provided.

[0006] Also, in the torque endpoint detection method, the endpoint of polishing is indirectly detected from the torque of the rotating shaft generated by the difference in the friction coefficient between materials (for example, see Patent Document 1).

Prior Art Documents

[0007] [Patent Document 1] Japanese Patent Application Publication No. 06-315850 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The difference in polishing speed between the polishing target film and the stopper film (hereinafter also referred to as the "selectivity ratio") depends on the slurry used. Therefore, in the torque endpoint detection method, there is a problem in that the endpoint cannot be accurately detected unless an appropriate slurry is selected. However, no technology has been proposed to solve this problem from the perspective of the polishing pad configuration.

[0009] This invention has been made in view of the above-mentioned problems, and aims to provide a polishing pad that has low slurry dependence of selectivity ratio and can be used for highly accurate torque endpoint detection, and a method for manufacturing polished works using the same. [Means for solving the problem]

[0010] As a result of diligent research to solve the above problems, the inventors of the present invention have found that the above problems can be solved by using a polishing pad having polishing surfaces with different coefficients of dynamic friction between oxide films such as silicon oxide films and nitride films such as silicon nitride films, and have completed the present invention.

[0011] In other words, the present invention is as follows. [1] The polishing layer contains a water-soluble organic compound having a carboxylic acid group and / or a sulfonic acid group. Polishing pad. [2] The content of the water-soluble organic compound is 0.01 to 10% by weight relative to the total amount of the polished layer. The polishing pad described in [1]. [3] The water-soluble organic compound is at least one selected from the group consisting of poly(meth)acrylic acid, malic acid, lactic acid, tartaric acid, gluconic acid, adipic acid, naphthalenesulfonic acid formalin condensate, laurylbenzenesulfonic acid, and salts thereof. The polishing pad according to [1] or [2]. [4] The water-soluble organic compound is ammonium polyacrylate or naphthalenesulfonic acid formalin condensate. The polishing pad according to any one of [1] to [3]. [5] The molecular weight of the water-soluble organic compound is 500 to 10,000. The polishing pad according to any one of [1] to [4]. [6] A polishing step of polishing an object to be polished having an oxide film and a nitride film using the polishing pad according to any one of [1] to [5] to obtain a polished product, and an end point detection step of performing end point detection by a torque method during the polishing. A method for manufacturing a polished product. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a polishing pad having low slurry dependence of the selectivity ratio and capable of being used for highly accurate torque detection type end point detection, and a method for manufacturing a polished product using the same. [Brief Description of the Drawings]

[0013] [Figure 1] It is a schematic cross-sectional view of the polishing pad of the present embodiment. [Figure 2] It is a schematic diagram showing a film thickness control system mounted on CMP. [Figure 3] It is a schematic diagram showing the measurement principle of end point detection by the torque method. [Modes for Carrying Out the Invention]

[0014] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. However, the present invention is not limited to this, and various modifications are possible without departing from the gist thereof.

[0015] 〔Polishing Pad〕 The polishing pad of the present embodiment includes a polishing layer containing a water-soluble organic compound having a carboxylic acid group and / or a sulfonic acid group (hereinafter also simply referred to as "water-soluble organic compound") in the polishing layer.

[0016] As shown in FIG. 1, the polishing pad 10 of the present embodiment includes a polishing layer 11 containing the water-soluble organic compound, and optionally includes a base material layer 12. By containing the water-soluble organic compound, the polishing layer 11 has different friction coefficients with respect to an oxide layer and a nitride layer. Therefore, in the torque end point detection method, it becomes possible to detect more accurately the difference in torque of the rotating shaft caused by the difference in friction coefficient between materials, and as a result, the accuracy of end point detection is further improved. Hereinafter, the detailed configuration will be described.

[0017] 〔Polishing Layer〕 The polishing layer 11 includes a polishing surface 11a for polishing the workpiece. The polishing layer is not particularly limited as long as it contains a resin that is the main component constituting the polishing layer and a water-soluble organic compound different from the resin. Examples of the configuration of the polishing layer include a foamed molded body of resin, a non-foamed molded body of resin, a resin-impregnated substrate, and the like. In these configurations, the water-soluble organic compound can be mixed with the resin that is the main component and used.

[0018] Here, the foamed molded body of resin refers to a foam composed of a predetermined resin without a fiber substrate. The foamed shape is not particularly limited, and examples include spherical bubbles, substantially spherical bubbles, tear-shaped bubbles, or continuous bubbles in which each bubble is partially connected.

[0019] Furthermore, a non-foamed resin molded article refers to a non-foamed article that does not have a fibrous base material and is composed of a predetermined resin. A non-foamed article refers to one that does not have bubbles as described above. In this embodiment, a non-foamed resin molded article also includes one in which a curable composition is attached to a base material such as a film and cured. More specifically, cured resin products formed by methods such as the lavia coater method, small-diameter gravure coater method, reverse roll coater method, transfer roll coater method, kiss coater method, die coater method, screen printing method, and spray coating method are also included in the non-foamed resin molded article.

[0020] Furthermore, a resin-impregnated substrate refers to a material obtained by impregnating a fibrous substrate with resin. Here, the fibrous substrate is not particularly limited, but examples include woven fabrics, nonwoven fabrics, and knitted fabrics.

[0021] (Water-soluble organic compound) Water-soluble organic compounds are used to adjust the coefficient of friction for oxide films such as silicon oxide films and nitride films such as silicon nitride films. By using water-soluble organic compounds, the friction adjustment function of the organic compounds is realized in the presence of slurry, making it possible to detect differences in the torque of the rotating shaft caused by differences in the coefficient of friction between materials with higher accuracy in torque endpoint detection methods.

[0022] The water-soluble organic compounds having a carboxylic acid group are not particularly limited, but examples include poly(meth)acrylic acid, malic acid, lactic acid, tartaric acid, gluconic acid, adipic acid, and salts thereof.

[0023] The water-soluble organic compounds having a sulfonic acid group are not particularly limited, but examples include naphthalene sulfonic acid formalin condensate, laurylbenzenesulfonic acid, and salts thereof.

[0024] Among these, poly(meth)acrylic acid, naphthalene sulfonic acid formalin condensate, and salts thereof are more preferred, and ammonium polyacrylate and naphthalene sulfonic acid formalin condensate are even more preferred. Using such water-soluble organic compounds tends to improve the detection accuracy in the torque endpoint detection method. The water-soluble organic compound may be used alone or in combination of two or more.

[0025] Furthermore, the molecular weight of the water-soluble organic compound is preferably 90 to 15,000, more preferably 500 to 10,000, and even more preferably 500 to 2,000. Having the molecular weight within the above range tends to improve the detection accuracy in the torque endpoint detection method. Note that if the water-soluble organic compound is a polymer, the "molecular weight of the water-soluble organic compound" refers to the number-average molecular weight of the polymer.

[0026] The content of the water-soluble organic compound is preferably 0.01 to 10% by weight, more preferably 0.05 to 5% by weight, and even more preferably 0.1 to 3% by weight, relative to the total amount of the polished layer. When the content of the water-soluble organic compound is within the above range, the endpoint detection accuracy in the torque endpoint detection method tends to improve. Note that "content of water-soluble organic compound" refers to the total content when multiple water-soluble organic compounds are used.

[0027] (resin) Examples of the resins that make up the main component of the abrasive layer include wet-coagulable resins, dry-coagulable resins, and other curable resins. These resins may be used individually or in combination of two or more types.

[0028] Here, "wet solidification" refers to a method of solidifying and regenerating the resin in the impregnated resin solution by impregnating a fibrous substrate with a resin solution containing dissolved resin, and then immersing it in a tank of solidification liquid (water, which is a poor solvent for the resin). Alternatively, a molded resin body without a fibrous substrate may be obtained by coating a film with a resin solution containing dissolved resin and immersing it in a tank of solidification liquid. In this wet solidification, the resin in the resin solution aggregates and solidifies as the solvent in the resin solution is replaced by the solidification liquid. Bubbles are formed in areas other than where the resin has aggregated and solidified. The shape of the formed bubbles is not particularly limited, but they tend to be teardrop-shaped.

[0029] Furthermore, "dry solidification" refers to a method in which a liquid containing a prepolymer and a curing agent is impregnated into a fibrous substrate, and the prepolymer and curing agent react to form a resin. Alternatively, a liquid containing a prepolymer and a curing agent may be applied to a film or the like, and the prepolymer and curing agent may react to obtain a molded resin body that does not contain a fibrous substrate. In this wet solidification method, a foamed product is obtained when gas is generated by the reaction between the prepolymer and the curing agent, or when a foaming agent is used, and a non-foamed product is obtained otherwise. The shape of the foam is not particularly limited, but it tends to be spherical or nearly spherical.

[0030] The following are examples of specific resins, but the resins constituting the polishing layer in this embodiment are not limited to those listed below.

[0031] The resins that can be wet-coagulated are not particularly limited, but examples include polyurethane resins such as polyurethane and polyurethane polyurea; acrylic resins such as polyacrylate and polyacrylonitrile; vinyl resins such as polyvinyl chloride, polyvinyl acetate and polyvinylidene fluoride; polysulfone resins such as polysulfone and polyethersulfone; acylated cellulose resins such as acetylated cellulose and butyrylated cellulose; polyamide resins; and polystyrene resins.

[0032] Among these, it is preferable to include a polyurethane resin. The polyurethane resin is not limited to the following, but examples include polyester-based polyurethane resin, polyether-based polyurethane resin, and polycarbonate-based polyurethane resin. Using such resins tends to further improve the polishing rate.

[0033] The prepolymers constituting the dry-solidifiable resin are not particularly limited, but examples include adducts of hexamethylene diisocyanate and hexanetriol; adducts of 2,4-tolylene diisocyanate and polyoxytetramethylene glycol; adducts of tolylene diisocyanate and hexanetriol; adducts of tolylene diisocyanate and trimethylolpropane; adducts of xylylene diisocyanate and trimethylolpropane; adducts of hexamethylene diisocyanate and trimethylolpropane; and adducts of isocyanuric acid and hexamethylene diisocyanate. The prepolymers may be used alone or in combination of two or more.

[0034] The curing agent for a dry-curing resin is not particularly limited, but examples include amine compounds such as 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4-methyl-2,6-bis(methylthio)-1,3-benzenediamine, 2-methyl-4,6-bis(methylthio)-1,3-benzenediamine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 2,2-bis[3-(isopropylamino)-4-hydroxyphenyl]propane, 2,2-bis[3-(1-methylpropylamino)-4-hydroxyphenyl]propane, 2,2-bis[3-(1-methylpentylamino)-4-hydroxyphenyl]propane, 2,2-bis(3,5-diamino-4-hydroxyphenyl)propane, 2,6-diamino-4-methylphenol, trimethylethylenebis-4-aminobenzoate, and polytetramethylene oxide-di-p-aminobenzoate; ethylene glycol, propylene Examples of polyhydric alcohol compounds include glycerin glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-4,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, trimethylolpropane, trimethylolethane, and trimethylolmethane. The hardening agent may be used alone or in combination of two or more types.

[0035] Other compositions constituting the curable resin are not particularly limited, but may include, for example, a photocurable composition containing a photopolymerization initiator and a polymerizable compound, a thermosetting composition containing a thermal polymerization initiator and a polymerizable compound, a thermosetting resin, a UV curable resin, or a curable composition containing a two-component mixed type curable resin. The curable composition may also optionally contain a crosslinking agent having two or more polymerizable functional groups.

[0036] The polymerizable compounds mentioned above are not particularly limited, but examples include (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate.

[0037] The above-mentioned photopolymerization initiators are not particularly limited, but examples include benzophenone compounds, acetophenone compounds, and thiothisanthone compounds. The thermal polymerization initiators are not particularly limited, but examples include azo compounds such as 2,2'-azobisbutyronitrile and peroxides such as benzoyl peroxide (BPO).

[0038] The thermosetting resins mentioned above are not particularly limited, but examples include phenolic resins, epoxy resins, acrylic resins, urea resins, and formaldehyde resins.

[0039] The above-mentioned UV-curing resin is not particularly limited, but examples include prepolymers with a number average molecular weight of about 1,000 to 10,000, such as acrylic (methacrylic) esters and their urethane-modified products, and thiocol compounds. Reactive diluents and organic solvents can be used as appropriate depending on the application.

[0040] Furthermore, the two-component curing resin is not particularly limited, but for example, prepolymers with different physical properties can be used.

[0041] [Base material layer] The polishing pad of this embodiment has a base layer on the side opposite to the polishing surface of the polishing layer. The presence of a base layer improves the ability to conform to the workpiece and also tends to improve the uniformity of the polishing pressure applied to the workpiece.

[0042] The base layer is not particularly limited, but examples include impregnated nonwoven fabrics and resin foams made by impregnating resins. Examples of impregnated nonwoven fabrics include polyolefin-based, polyamide-based, and polyester-based nonwoven fabrics impregnated with resins such as polyurethane, polyurethane polyurea, acrylic, polyacrylate, and polyacrylonitrile, vinyl, polyvinyl chloride, polyvinyl acetate, and polyvinylidene fluoride, polysulfone, polyethersulfone, acylated cellulose, acetylated cellulose, and butyrylated cellulose, polyamide, and polystyrene. Examples of resin foams include polyolefin-based foams, polyurethane-based foams, polystyrene-based foams, phenol-based foams, synthetic rubber-based foams, and silicone rubber-based foams.

[0043] [Method for manufacturing polishing pads] Methods for manufacturing the polishing pad of this embodiment include known methods such as bonding the polishing layer and the base layer together, or forming the polishing layer on the base layer.

[0044] The method for forming the polishing layer is not particularly limited, but examples include the wet solidification method described above, the dry solidification method described above, and a method for curing a curable resin. In this embodiment, a method for incorporating a compound having a carboxylic acid group and / or a sulfonic acid group into the polishing layer is to mix the compound having a carboxylic acid group and / or a sulfonic acid group with the resin before curing and then cure it in that state.

[0045] The method for forming the base layer is not particularly limited, but examples include forming each of the above-mentioned foams by known methods.

[0046] [Method for manufacturing polished products] The method for manufacturing a polished workpiece according to this embodiment includes a polishing step of polishing an object to be polished using the above-mentioned polishing pad to obtain a polished workpiece, and an endpoint detection step of performing endpoint detection using a torque method during the polishing process.

[0047] [Polishing process] The polishing process may be primary lapping (rough lapping), secondary lapping (finishing lapping), primary polishing (rough polishing), secondary polishing (finishing polishing), or a process that combines these polishing steps. Here, "lapping" refers to polishing with coarse abrasive grains at a relatively high rate, while "polishing" refers to polishing with fine abrasive grains at a relatively low rate to improve surface quality.

[0048] Among these, the polishing pad of this embodiment is preferably used for chemical mechanical polishing. On the other hand, it can also be used to hold the workpiece in machining processes such as grinding and cutting. The method for manufacturing the polished product of this embodiment will be described below using chemical mechanical polishing as an example, but the method for manufacturing the polished product of this embodiment is not limited to the following.

[0049] The objects to be polished are not particularly limited, but examples include materials for semiconductor devices and electronic components, particularly Si substrates (silicon wafers), SiC (silicon carbide) substrates, GaAs (gallium arsenide) substrates, glass, and thin substrates (objects to be polished) such as hard disks and LCD (liquid crystal display) substrates.

[0050] The polishing method can be any conventionally known method and is not particularly limited. For example, first, the workpiece to be polished, held in a holding platen positioned opposite the polishing pad, is pressed against the polishing surface, and the polishing pad and / or holding platen are rotated while a slurry is supplied from the outside. The polishing pad and the holding platen may rotate in the same direction at different rotational speeds, or they may rotate in different directions. In addition, the workpiece to be polished may move (rotate) inside the frame during the polishing process.

[0051] The slurry may contain water, chemical components such as oxidizing agents represented by hydrogen peroxide, additives, abrasive grains (polishing particles; for example, SiC, SiO2, Al2O3, CeO2), etc., depending on the workpiece to be polished and the polishing conditions.

[0052] [Endpoint detection process] The manufacturing method for polished products of this embodiment includes an endpoint detection step in the polishing step, in which the endpoint is detected using a torque method. Specifically, a conventionally known method can be used as the endpoint detection method using a torque method. Figure 2 shows a schematic diagram of the torque method endpoint detection method. This schematic diagram shows a chemical mechanical polishing process in which a wafer W held by a top ring 21 is pressed onto a polishing pad 10 attached to a table 22 while a slurry (not shown) is flowed over it, thereby grinding and flattening the target film on the surface of the wafer W. The polishing apparatus 20 is equipped with a torque detection type film thickness detection sensor 23 around the top ring 22 in order to perform an endpoint check and complete the process with high accuracy. The wafer W has a film to be polished W1 and a stopper film W2 placed on the base of the film to be polished.

[0053] Examples of the polishing target film W1 and stopper film W2 include silicon oxide film and silicon nitride film.

[0054] In the torque method, the change in the friction coefficient between the wafer W and the polishing pad 10 is detected as a change in the rotational shaft torque of the top ring 21 or table 22. The torque change can be detected, for example, by measuring the drive motor current of the rotational shaft of the top ring 21 or table 22. More specifically, as shown in Figure 3, when polishing is performed and the polishing target film W1 is removed (STEP 1), the lower stopper film W2 is exposed and the torque change is detected (STEP 2). In the torque method, the endpoint is detected by detecting this torque change. In the torque method, the torque change tends to depend on the selection of the slurry, so it is preferable to select the slurry in advance from the viewpoint of accurate endpoint detection. [Examples]

[0055] The present invention will be described more specifically below using examples and comparative examples. The present invention is not limited in any way by the following examples.

[0056] (Example 1) A prepolymer containing an adduct of 2,4-tolylene diisocyanate and polyoxytetramethylene glycol was prepared by adding ammonium polyacrylate (number average molecular weight 1000) as an interacting compound to a concentration of 0.5% by weight relative to the total amount of resin. 3,3'-dichloro-4,4'-diaminodiphenylmethane was added as a curing agent, and the mixture was cured to form a polishing layer. The base layer was obtained by impregnating a nonwoven fabric made of polyethylene fibers with a polyurethane resin solution, followed by wet solidification and drying. The polishing pad of Example 1 was obtained by bonding the base layer to the polishing layer using double-sided tape having a hot-melt adhesive layer.

[0057] (Examples 2-6) Polishing pads for Examples 2 to 6 were obtained using the same manufacturing method as in Example 1, except that the type and amount of interacting compounds were changed as shown in Table 1.

[0058] (Comparative Example 1) The polishing pad of Comparative Example 1 was obtained by the same manufacturing method as in Example 1, except that ammonium polyacrylate (number average molecular weight 1000), which is an interacting compound, was not used.

[0059] (Comparative Example 2) A conventionally known polishing pad, IC1000 (manufactured by Nitta Haas Corporation), was used.

[0060] (Measurement of the coefficient of kinetic friction) The polishing pads of the examples and comparative examples were roughened on a dresser fitted with a #160 grit diamond grinding wheel for 30 minutes. After surface roughening, the samples were cut into 20 mm x 10 mm strips, and the resistance force was measured by reciprocating a slider with a constant load of 5 g applied to the sample using a reciprocating friction tester (HEIDON-14D). The sliders used were silicon oxide and silicon nitride, each with sides of 5 mm, and moved at a speed of 1 mm / sec over a 12 mm range. Measurements were taken by reciprocating 10 times for each sample and load, and the average of the 10th load was used to determine the coefficient of dynamic friction μ. O and μ N I requested it.

[0061] [Table 1]

[0062] In all of Examples 1-6, the additive ammonium polyacrylate or naphthalene sulfonic acid formalin condensate specifically adsorbed onto the silicon nitride film, increasing the frictional resistance of the silicon nitride film and decreasing the frictional resistance against the silicon oxide film, thus reducing the dynamic friction coefficient μ against the silicon oxide film. O and the coefficient of dynamic friction μ for silicon nitride film N Ratio μ N / μ O The increased size allowed for accurate torque-based endpoint detection. [Industrial applicability]

[0063] The polishing pad of the present invention has industrial applicability as a pad that can be used for polishing optical materials, semiconductor devices, glass substrates for hard disks, etc., and is particularly suitable for polishing devices on which oxide layers, metal layers, etc. are formed on semiconductor wafers. [Explanation of symbols]

[0064] 10: Polishing pad, 11: Polishing layer, 11a: Polishing surface, 12: Substrate layer, 20: Polishing device, 21: Top ring, 22: Table, 23: Film thickness detection sensor, W: Wafer, W1: Film to be polished, W2: Stopper film

Claims

1. The polishing layer contains a water-soluble organic compound having a carboxylic acid group and / or a sulfonic acid group. Includes no transparent window components. Polishing pad for torque-type endpoint detection.

2. The content of the water-soluble organic compound is 0.01 to 10% by weight relative to the total amount of the polished layer. The polishing pad according to claim 1.

3. The aforementioned water-soluble organic compound is at least one selected from the group consisting of poly(meth)acrylic acid, malic acid, lactic acid, tartaric acid, gluconic acid, adipic acid, naphthalene sulfonic acid formalin condensate, laurylbenzenesulfonic acid, and salts thereof. The polishing pad according to claim 1 or 2.

4. The aforementioned water-soluble organic compound is ammonium polyacrylate or naphthalene sulfonic acid formalin condensate. A polishing pad according to any one of claims 1 to 3.

5. The molecular weight of the aforementioned water-soluble organic compound is 500 to 10000. A polishing pad according to any one of claims 1 to 4.

6. The polishing step includes polishing an object having an oxide film and a nitride film using a polishing pad according to any one of claims 1 to 5 to obtain a polished workpiece, and an endpoint detection step includes detecting the endpoint using a torque method during the polishing process. A method for manufacturing polished products.

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