Resin polishing composition and polishing method

Abstract

The present invention provides an abrasive composition that allows for high polishing speeds without using high-hardness abrasive grains when polishing resins, and that minimizes damage such as scratches to the material being polished. [Solution] The present invention provides an abrasive composition for resins, comprising abrasive particles, an alkaline agent, and an oxidizing agent, wherein the abrasive particles are silica fine particles, the alkaline agent is one or more selected from ammonia, alkanolamine, and hydrazine, and the oxidizing agent is hydrogen peroxide and / or peroxodisulfate, and the composition contains 0.5 to 15% abrasive particles, 0.5 to 15% alkaline agent, and 0.2 to 5% oxidizing agent, and has a pH of 10 or higher.

Description

Technical Field

[0001] The present invention relates to a polishing composition for resins.

Background Art

[0002] In the semiconductor field, with the miniaturization and multilayerization of wiring circuits, planarization of the wafer surface has become important, and CMP (Chemical Mechanical Polishing) is used for planarization. CMP combines the chemical action of chemicals and the mechanical action of abrasive grains to polish and planarize the surface of the target material.

[0003] In recent years, although semiconductor chips with wiring widths less than a few nm have been developed, as further miniaturization progresses, there are many problems in manufacturing and mass production. Therefore, instead of miniaturizing the wiring in the chip itself, technologies have been developed to package multiple chips in combination to achieve high performance. In a packaging substrate, the connection and wiring between chips are performed via an interposer, and it is common to use a silicon interposer using silicon as the interposer. On the other hand, since silicon is expensive, in recent years, an organic interposer (RDL) that forms a wiring layer using a lower-cost resin has been developed.

[0004] Polyimide is generally used as the resin for RDL, and a damascene process is used to form the wiring layer in the same manner as in the previous process of semiconductor chip manufacturing. In the damascene process of RDL, as the wiring is miniaturized, the flatness of the resin surface becomes important, and thus CMP is used. However, polyimide is a very hard material and is chemically stable, so it is difficult to perform chemical etching by chemicals, and in many cases, it relies on the mechanical polishing action of hard abrasive grains during polishing to obtain an appropriate wire polishing rate.

[0005] For example, Patent Document 1 reports a technique that uses alumina abrasive grains, which have higher hardness, in addition to silica abrasive grains. However, when using high-hardness abrasive grains for polishing, there are problems such as scratches caused by the abrasive grains damaging the surface of the object to be polished, and when copper wiring and polyimide are polished simultaneously, erosion and dishing due to reduced selectivity are likely to occur.

[0006] Non-patent document 1, which examines the chemical effects of polishing compositions, shows that using ethylenediamine as an alkaline agent in addition to colloidal silica increases the polishing rate. However, this document states that an ethylenediamine addition amount of 20% or more is required for polishing. Since ethylenediamine is highly chemically corrosive and has a significant impact on the human body, there is a need for a polishing composition that can achieve effective polishing even at lower concentrations.

[0007] Furthermore, Patent Document 2 shows an abrasive composition for polyimide that contains (a) an oxidizing agent and (b) abrasive grains, and preferably further contains (c) a pH adjuster, but a more high-performance abrasive composition is desired. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2021-107479 [Patent Document 2] Japanese Patent Publication No. 2009-224695 [Non-patent literature]

[0009] [Non-Patent Document 1] Gi-Ppeum Jeong, Jun-Seong Park et al., Scientifc Reports, 12, Article number: 3366(2022). [Overview of the project] [Problems that the invention aims to solve]

[0010] The object of the present invention is to provide an abrasive composition that can achieve a high polishing speed without using high-hardness abrasive grains, suppresses surface roughness, and causes less damage such as scratches to the material to be polished. [Means for solving the problem]

[0011] This invention was made to solve the above-mentioned problems and can be realized in the following forms. [1] A polishing composition for resins, comprising abrasive particles, an alkaline agent, and an oxidizing agent, wherein the abrasive particles are silica fine particles, the alkaline agent is one or more selected from ammonia, alkanolamine, and hydrazine, and the oxidizing agent is hydrogen peroxide and / or peroxodisulfate, This polishing composition is characterized by containing 0.5-15% abrasive particles, 0.5-15% alkaline agent, and 0.2-5% oxidizing agent, and having a pH of 10 or higher. [2] The polishing composition is characterized in that the alkaline agent is ammonia and an alkanolamine. [3] The polishing composition according to [1] or [2], further characterized in that it contains 0.01 to 2% of one or more ethylenically unsaturated carboxylic acid polymers as a polymer electrolyte. [4] The polishing composition of [3] is characterized in that the ethylenically unsaturated carboxylic acid polymer is one or more selected from acrylic acid polymer, itaconic acid polymer, maleic acid and itaconic acid polymer, and acrylic acid and maleic acid polymer. [5][1] This polishing method is characterized by polishing a resin surface using the polishing composition described in [5][1]. [6] The polishing method according to [5], characterized in that an oxidizing agent is added after abrasive grains and an alkaline agent are added. [Effects of the Invention]

[0012] By using the present invention, it is possible to provide a polishing composition that can achieve a high polishing speed, suppress surface roughness, and cause less damage such as scratches to the material being polished. [Modes for carrying out the invention]

[0013] The following describes in detail embodiments for carrying out the present invention, but the present invention is not limited to these. The present invention relates to an abrasive composition for resins, comprising abrasive particles, an alkaline agent, and an oxidizing agent.

[0014] In the present invention, the object to be polished with the polishing composition is not particularly limited, but the main target is resin material, and the target resin material is a surface containing epoxy material or polyimide material. Among these, it is preferable to apply it to a surface containing polyimide material. Polyimide is a polymer compound having imide ring bonds in its molecular chain, and is broadly classified into thermosetting type and thermoplastic type, but the present invention is applicable to both.

[0015] In the polishing composition of the present invention, it is preferable to use silica fine particles as abrasive particles, considering the physical effect on the material to be polished. Both fumed silica and colloidal silica can be used as silica fine particles, but colloidal silica is more preferable from the viewpoint of polishability. While fumed silica yields a higher polishing speed compared to colloidal silica, it is more prone to causing scratches. Furthermore, using alumina or other materials other than those of the present invention as abrasive particles is undesirable because it is also prone to causing scratches.

[0016] There are no restrictions on the particle size of the silica fine particles in this invention, but generally, a primary particle size of less than 500 nm is preferred. While particle sizes exceeding 500 nm increase the polishing speed, they are undesirable because they worsen the surface roughness.

[0017] The content of silica fine particles in the polishing composition of the present invention is preferably 0.5 to 15% as an active ingredient. A higher content increases the polishing rate, but above this content range, scratches increase, and the stability of the slurry decreases and costs increase. On the other hand, if the content is less than this range, the polishing speed decreases.

[0018] The alkali agent in the polishing composition of the present invention is preferably at least one selected from ammonia, hydrazine, and alkanolamine. Among them, ammonia and alkanolamine are preferable, and it is particularly preferable to use ammonia and alkanolamine in combination from the viewpoints of polishing rate and surface roughness. By using these alkali agents, the resin surface can be hydrolyzed and the polishing rate can be improved.

[0019] The alkanolamine of the present invention is a compound having a hydroxy group and an amino group in an alkane skeleton, and examples thereof include ethanolamine, heptanolamine, isoethaline, propanolamine, sphingosine, methanolamine, dimethylethanolamine, N-methylethanolamine, and the like. From the viewpoints of polishing rate and surface roughness, it is preferable to use monoethanolamine.

[0020] These alkali agents may be used alone or in combination of two or more.

[0021] The content of the alkali agent in the polishing composition of the present invention is preferably 0.5 to 15% as an active ingredient, and particularly preferably 1 to 13%. If the content of the alkali agent is outside this range, the polishing rate decreases.

[0022] The polishing composition of the present invention preferably has a pH of 10 or more. When the pH is less than 10, the hydrolysis action weakens and the polishing rate decreases.

[0023] In the present invention, in a process that is not greatly affected by metal ions during polishing, in addition to the above alkali agent, sodium hydroxide, potassium hydroxide, etc. may be used in combination.

[0024] The oxidizing agent contained in the polishing composition of the present invention is preferably a peroxide, and among these, hydrogen peroxide and peroxodisulfate are particularly preferred. By using these oxidizing agents, the surface of the resin can be oxidized and decomposed, thereby improving the polishing speed.

[0025] These oxidizing agents may be used individually or in combination of two or more. There are no particular restrictions on the peroxodisulfate, but metal-free salts such as ammonium peroxodisulfate are more preferable. This is because the presence of metal ions may alter the electrical properties of the object being polished.

[0026] The oxidizing agent content in the polishing composition of the present invention is preferably 0.2 to 5%, and particularly preferably 0.5 to 3%, as an active ingredient. If the oxidizing agent content is outside this range, the polishing speed decreases. Furthermore, since the addition of an oxidizing agent reduces the stability of the slurry, it is preferable to mix the oxidizing agent immediately before polishing.

[0027] The polishing composition of the present invention preferably further contains a polymer electrolyte to improve the dispersibility of the abrasive particles. Improving the dispersibility of the abrasive particles enhances the stability of the composition, as well as improving the polishing speed and flatness.

[0028] The polymer electrolyte that can be used in the present invention preferably contains one or more ethylenically unsaturated carboxylic acid polymers. Examples of monomers of ethylenically unsaturated carboxylic acids include (meth)acrylic acid, maleic acid, fumaric acid, and itaconic acid. Furthermore, the monomers of ethylenically unsaturated carboxylic acids may be polymerized individually, or two or more different monomers may be copolymerized. Polymerization of ethylenically unsaturated carboxylic acid monomers individually refers to, for example, a homopolymer formed by the polymerization of acrylic acid monomers. Copolymerization of monomers of different types of ethylenically unsaturated carboxylic acids refers to, for example, a copolymer formed by the copolymerization of acrylic acid and maleic acid. Preferably, the polymer is an ethylenically unsaturated carboxylic acid polymer with (meth)acrylic acid, maleic acid, maleic anhydride, or itaconic acid as monomers. Specifically, these are acrylic acid polymers, itaconic acid polymers, polymers of maleic acid and itaconic acid, and polymers of acrylic acid and maleic acid, with itaconic acid polymers, polymers of maleic acid and itaconic acid, and polymers of acrylic acid and maleic acid being particularly preferred. These polymer electrolytes may be used individually or in combination of two or more types.

[0029] There are no particular restrictions on the molecular weight of these polyelectrolytes, but they are usually between 500 and 100,000, preferably between 1,000 and 50,000. The content of the polymer electrolyte in the composition of the present invention is not particularly limited, but is preferably 0.01 to 2%, particularly preferably 0.02 to 1.5%, and most preferably 0.04 to 1% as an active ingredient. If the content of the polymer electrolyte is outside the above range, a sufficient dispersion effect cannot be obtained, and contact between the abrasive grains and the material to be polished may be hindered, resulting in a decrease in polishing speed.

[0030] In the present invention, when polishing the resin and wiring material simultaneously, it is desirable to incorporate a corrosion inhibitor for the wiring material. The most common wiring material is copper, and azole compounds can be incorporated as corrosion inhibitors for copper. Examples of azole compounds include toltriazole, benzotriazole, substituted benzotriazole, and mercaptobenzothiazole.

[0031] The amount of corrosion inhibitor can be adjusted considering the polishing speed of the resin material, the polishing speed of the dashed material, erosion, dishing, etc. The typical amount of corrosion inhibitor is usually 0.1-10%.

[0032] A surfactant may be added to improve the contact efficiency between the abrasive grains and the resin being polished.

[0033] In the present invention, various additives may be added as long as they do not inhibit polishing. Examples of additives include, but are not limited to, pH adjusters such as potassium hydroxide, chelating agents, pigments, preservatives, defoaming agents, and thickeners.

[0034] The present invention relates to a polishing method characterized by polishing a resin surface using the above-mentioned polishing composition. Furthermore, it relates to a polishing method characterized by adding an oxidizing agent after adding abrasive particles and an alkaline agent.

[0035] The polishing method of the present invention is characterized by supplying the polishing composition of the present invention to a polishing pad and rotating a polishing platen to polish the resin while bringing the polishing pad into contact with the polishing surface.

[0036] The polishing apparatus applicable to the present invention can be a general polishing apparatus comprising a holder for holding resin and a polishing platen to which a polishing pad is attached (equipped with a motor that can change the rotation speed, etc.). For example, it can be used with a wide range of equipment, from large devices such as the F-REX300 manufactured by Ebara Corporation to small research-use polishing apparatuses such as the MA-200e manufactured by Musashino Electronics Co., Ltd.

[0037] The polishing pads that can be used in this invention are not particularly limited, but for example, Nitta DuPont IC1000 or IC1400 can be used.

[0038] In the polishing method of the present invention, the polishing pressure, i.e., the contact pressure between the surface to be polished and the polishing pad, is 10 to 10000 gf / cm². 2 It is preferable to perform polishing with a solvent of 100-2000 gf / cm². 2It is more preferable to perform polishing with 200-1000 gf / cm². 2 Polishing is most preferable.

[0039] In the polishing method of the present invention, it is preferable to perform polishing at a rotation speed of 20 to 200 rpm for the polishing platen, and more preferably at 50 to 150 rpm.

[0040] In the polishing method of the present invention, while the resin is being polished, the polishing composition is continuously supplied to the polishing pad on the polishing platen using a pump or the like. There is no limit to the amount supplied, but it is preferable that the surface of the polishing pad is always covered with the polishing composition. This ensures that the polishing composition is evenly distributed across the polishing surface, resulting in high flatness after polishing. From this viewpoint, the amount of polishing liquid supplied to the polishing platen in the polishing method of the present invention is preferably 10 to 500 ml / min, and more preferably 20 to 200 ml / min.

[0041] In the polishing method of the present invention, the polishing composition can be diluted by adding water or an aqueous solution before use. Examples of dilution methods include adding water or an aqueous solution to the polishing composition, or merging a pipe supplying the polishing composition with a pipe supplying water or an aqueous solution and mixing them before supplying the diluted polishing solution to the polishing pad.

[0042] When performing the polishing method of the present invention, it is preferable to add the abrasive grains and alkaline agent first, and then the oxidizing agent, from the viewpoint of storage stability of the polishing composition. [Examples]

[0043] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

[0044] [Test equipment] A Musashino Electronics MA-200e was used as the polishing device. The polishing pad used was a Nitta DuPont IC1000.

[0045] [substrate] A test substrate was created by attaching Toray's Kapton tape to a 30mm diameter (1mm thick) glass substrate.

[0046] [Polishing test] The substrate prepared as described above was placed in the apparatus, and polishing was performed for 5 minutes while supplying slurry at a rate of 40 mL / min. The workpiece rotation speed during polishing was 100 rpm, and the polishing pad rotation speed was 100 rpm. The pressure during polishing was 850 gf / cm². 2 That was the case. The polishing speed was calculated from the weight change before and after polishing. Surface roughness (Ra) was measured using an AFM (AFM5100N: Hitachi High-Tech). The presence or absence of scratches was confirmed by SEM and visual inspection.

[0047] [Medications] <Abrasive grains> PL-10H (Colloidal silica 20% slurry, manufactured by Fuso Chemical Industries) Alumina abrasive grains (0.5 μm, reagent: manufactured by Fujifilm Wako Pure Chemical Industries) <Oxidizing agent> 30% hydrogen peroxide (reagent: manufactured by Fujifilm Wako Pure Chemical Industries) Ammonium peroxodisulfate (APS, Reagent: Manufactured by Fujifilm Wako Pure Chemical Industries) <Alkaline agent> 28% aqueous ammonia (reagent: manufactured by Fujifilm Wako Pure Chemical Industries) Monoethanolamine (Reagent: Manufactured by Fujifilm Wako Pure Chemical Industries) 80% hydrazine monohydrate (reagent: manufactured by Fujifilm Wako Pure Chemical Industries) Ethylenediamine (Reagent: Manufactured by Fujifilm Wako Pure Chemical Industries) 3-Methoxypropylamine (Reagent: Manufactured by Fujifilm Wako Pure Chemical Industries) <Polymer electrolyte> P-MA / IA (Maleic acid and itaconic acid polymer, molecular weight Mw=2000, proprietary product, active ingredient: 40%) P-IA (Itaconic acid polymer, molecular weight Mw=20000, proprietary product, active ingredient: 30%) P-AA (Acrylic acid polymer, Aron A-20UK, manufactured by Toagosei, active ingredient: 40%) P-AA / MA (polymer of acrylic acid and maleic acid, Poise 520, manufactured by Kao Corporation, active ingredient: 40%) AA-AMPS (Acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, proprietary manufacturing, molecular weight Mw=10000, active ingredient: 40%) <Other> Ethanol (Reagent: Manufactured by Fujifilm Wako Pure Chemical Industries)

[0048] Examples and comparative examples are shown in Tables 1-3. The polishing compositions were prepared by adding and mixing the ingredients in the order of the numbers listed in the table, and the remainder was prepared with deionized water. Note that a higher polishing speed indicates better performance, and a lower surface roughness indicates better performance. ○ indicates no scratches, and × indicates scratches. In addition, since surface roughness generally increases with increasing polishing speed, the polishing speed / surface roughness ratio is expressed to show the effect when using the polishing composition of the present invention.

[0049] As shown in Examples 1 to 13, when the polishing composition of the present invention was used, the polishing speed was 400 nm / min or more, and the surface roughness was 5 nm, indicating excellent flatness. Furthermore, as shown in Example 13, when ammonia and alkanolamine were used in combination as alkaline agents, the polishing speed was greatly improved.

[0050] On the other hand, when the abrasive content was outside the range, as in Comparative Examples 1 and 2, the polishing speed decreased and scratches occurred. Also, when alumina was used as the abrasive, as in Comparative Example 3, scratches occurred and surface roughness increased. When the oxidizing agent content was outside the range, as in Comparative Examples 4 to 7, the polishing speed decreased and surface roughness increased compared to the examples. As in Comparative Example 8, when the pH was less than 10, the polishing speed decreased significantly. Furthermore, when the alkaline agent content was outside the range, as in Comparative Examples 9 and 10, or when the alkaline agent was other than that of the present invention, as in Comparative Examples 11 and 12, the polishing speed decreased.

[0051] As shown in Examples 14-23, the polishing speed was improved when a specific amount of polymer electrolyte was further added to the polishing composition of the present invention. Furthermore, as shown in Example 23, the polishing speed was greatly improved when a polymer electrolyte was included and ammonia and alkanolamine were used in combination. In addition, the polishing speed / surface roughness ratio was the highest, demonstrating that surface roughness could be maintained while improving the polishing speed. Furthermore, as shown in Reference Example 1, when the polymer electrolyte content was outside the range, the polishing speed decreased significantly. Also, as shown in Reference Examples 3 and 4, when the polishing composition contained alcohol, the polishing speed decreased significantly.

[0052] [Table 1]

[0053] [Table 2]

[0054] [Table 3]

Claims

1. A polishing composition for resins, comprising abrasive particles, an alkaline agent, and an oxidizing agent, wherein the abrasive particles are silica fine particles, the alkaline agent is one or more selected from ammonia, alkanolamine, and hydrazine, and the oxidizing agent is hydrogen peroxide and / or peroxodisulfate. An abrasive composition characterized by containing 0.5 to 15% abrasive particles, 0.5 to 15% alkaline agent, and 0.2 to 5% oxidizing agent, with a pH of 10 or higher.

2. A polishing composition characterized in that the alkaline agent is ammonia and an alkanolamine.

3. The polishing composition according to claim 1 or 2, characterized in that the polishing composition further contains 0.01 to 2% of one or more ethylenically unsaturated carboxylic acid polymers as a polymer electrolyte.

4. The polishing composition of claim 3, characterized in that the ethylenically unsaturated carboxylic acid polymer is one or more selected from acrylic acid polymer, itaconic acid polymer, maleic acid and itaconic acid polymer, and acrylic acid and maleic acid polymer.

5. A polishing method characterized by polishing a resin surface using the polishing composition described in claim 1.

6. The polishing method according to claim 5, characterized in that an oxidizing agent is added after abrasive grains and an alkaline agent are added.

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