JP2008085058A - Additive for cmp abrasive, cmp abrasive, and substrate polishing method, and electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an additive for CMP abrasive for polishing the whole surface of a substrate flatly and evenly in a CMP technology for flattening a stepped substrate to be polished such as an interlayer insulation film and an insulation film for shallow trench isolation, and to provide a CMP abrasive which is a combination of the additive and a cerium oxide slurry, a polishing method, and an electronic device formed by polishing. <P>SOLUTION: The additive for CMP abrasive is an aqueous solution having a pH of 4-9 and contains an organic compound having an acetylenic linkage (carbon-carbon triple linkage), a water-soluble vinyl polymer, and water. The additive for CMP abrasive and the cerium oxide slurry for semiconductors are combined to form the CMP abrasive. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an additive for CMP (Chemical Mechanical Polishing) abrasive used in a planarization process of an interlayer insulating film or a shallow trench isolation formation process in a manufacturing process of an electronic component such as a semiconductor element, and CMP polishing. The present invention relates to an agent, a substrate polishing method, and an electronic component.

  Various microfabrication techniques have been researched and developed to increase the packaging density in the field of ultra-large scale integrated circuits, and the design rules are already in the order of sub-half microns. One of the techniques for satisfying such strict miniaturization requirements is a CMP polishing technique. Since this technique enables miniaturization by completely planarizing the layer to be exposed in the manufacturing process of a semiconductor device and improves the yield, for example, planarization of an interlayer insulating film or shallow trench This is a technique required when performing separation or the like.

  Conventionally, a LOCOS (silicon local oxidation) method has been used for element isolation in an integrated circuit, but in recent years, a shallow trench isolation method has been used to narrow the element isolation width. In the shallow trench isolation method, CMP is indispensable to remove the excess silicon oxide film formed on the wafer substrate, and a silicon nitride film is formed as a stopper under the silicon oxide film to stop polishing. It is common.

  As a CMP polishing agent for planarizing a silicon oxide insulating film or the like formed by a method such as plasma-CVD (Chemical Vapor Deposition) or low-pressure CVD in a semiconductor device manufacturing process, Alkaline abrasives having a pH of more than 9 using fumed silica as abrasive particles have been frequently used. However, in the silica polishing agent kept alkaline to increase the polishing rate of the silicon oxide film, the polishing rate of the silicon nitride film as a stopper is also high, and the entire surface of the wafer cannot be shaved uniformly (that is, high planarization cannot be performed). Alternatively, there are problems such as many polishing scratches that adversely affect electrical characteristics.

  On the other hand, abrasives using cerium oxide have been frequently used as glass surface abrasives for photomasks and lenses in recent years. This technique is disclosed in Patent Document 1, for example. Since cerium oxide abrasive has the features that the polishing rate of silicon oxide film is faster than silica abrasive and there are relatively few polishing flaws, studies have been made in recent years to apply cerium oxide abrasive as a semiconductor abrasive. Some of them are put to practical use as semiconductor abrasives. This technique is disclosed in, for example, Patent Document 2, but a cerium oxide abrasive that can planarize the entire surface of a semiconductor wafer on which various devices are formed, with almost no polishing scratches leading to poor electrical characteristics. Was not yet obtained.

In order to improve planarization using a cerium oxide abrasive, polishing is performed using a CMP abrasive comprising a cerium oxide slurry and an additive solution containing an aqueous solution of ammonium polyacrylate or amine polyacrylate as a dispersant. Then, it is proposed in Patent Document 3 that the flatness characteristics are improved, but when only the polyacrylic acid ammonium salt or the polyacrylic acid amine salt is used as the additive liquid, there is a problem in diffusion to the entire surface to be polished, It was found that unevenness occurred in the adsorptivity to the entire semiconductor wafer polishing surface, the uniformity of the polishing rate in the wafer surface was deteriorated, and the flatness in the wafer surface was varied.
JP-A-5-326469 JP-A-9-270402 No. 00/39843

  An object of the present invention is to improve the polishing uniformity over the entire surface of the wafer and to improve the planarization characteristics of the entire surface of the wafer. In order to help adsorb acid amine salt to the surface to be polished, the carbon-carbon triple bond portion of an organic compound having an acetylene bond (carbon-carbon triple bond) as an adsorbent is adsorbed on the entire surface of the film to be polished. This makes it possible to provide an additive for a CMP abrasive that can uniformly polish the entire surface of a semiconductor wafer, and a CMP abrasive and a polishing method using the same.

  The present invention relates to the following inventions (1) to (21).

  (1) Polishing an inorganic insulating film for a semiconductor by combining an organic compound having an acetylene bond, a water-soluble vinyl polymer, and water and having a pH of 4 to 9 and combining with a cerium oxide slurry for a semiconductor. An additive for CMP abrasives that is possible.

(2) The organic compound having an acetylene bond is represented by the general formula (I)

(In general formula (I), R ¹ represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, and R ² represents a substituted or unsubstituted alkyl group having 4 to 10 carbon atoms.) The additive for CMP abrasive | polishing agent of the said (1) description shown by these.

(3) The organic compound having an acetylene bond is represented by the general formula (II)

(In General Formula (II), R ^{3 to} R ⁶ each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, and R ⁷ and R ⁸ each independently represents 1 to 1 carbon atoms. 5 represents a substituted or unsubstituted alkylene group, and m and n each independently represents 0 or a positive number.) The additive for CMP abrasive according to (1) above.

  (4) The additive for CMP abrasive according to any one of (1) to (3), wherein the surface tension is 20 to 60 dyn / cm.

  (5) The above (1) to (1), wherein the vinyl polymer is at least one polymer selected from polyacrylic acid, ammonium polyacrylate, amine polyacrylate, polyvinyl acetate, polyvinyl imidazole, and polyvinyl pyrrolidone. The additive for CMP abrasives according to any one of (4).

  (6) The additive for CMP abrasives according to any one of (1) to (5) above, wherein the vinyl polymer has a weight average molecular weight of 100 to 200,000 (in terms of polyethylene oxide molecular weight).

  (7) The additive for CMP abrasives according to any one of (1) to (6), wherein the vinyl polymer is a polyacrylic acid ammonium salt or a polyacrylic acid amine salt.

  (8) The polyacrylic acid ammonium salt or amine salt is a polyacrylic acid ammonium salt or amine salt having a weight average molecular weight of 1,000 to 5,000, and a 5,000 to 20,000 polyacrylic acid ammonium salt or amine. The additive for CMP abrasives according to the above (7), which is composed of two kinds of ammonium polyacrylates or amine salts with a salt.

  (9) The additive for CMP abrasive according to any one of (1) to (8), wherein the organic compound having an acetylene bond has a molecular weight of 100 to 20,000.

  (10) The additive for CMP abrasive according to any one of (1) to (9) above, wherein the additive contains an organic compound having an acetylene bond in an amount of 0.05 to 5.0% by mass.

  (11) The additive for CMP abrasives according to any one of (1) to (10), wherein the additive contains a vinyl polymer in an amount of 0.05 to 3.0% by mass.

(12) The inorganic anions SO ₄ ²⁻ , NO ₃ ⁻ , Cl ⁻ and PO ₄ ³⁻ , which contain one or more kinds, and the total concentration thereof is 1 ppm to 1,000 ppm. The additive for CMP abrasives according to any one of (11).

(13) The additive for CMP abrasive according to any one of (1) to (12), wherein the contents of Na ⁺ , K ⁺ , Fe ³⁺ and Cu ²⁺ are all 1 ppm or less.

  (14) The substrate on which the film to be polished is formed is pressed against the polishing cloth of the polishing surface plate and pressed, and the substrate and the polishing cloth are relatively moved while supplying the CMP abrasive between the film to be polished and the polishing cloth. A method for polishing a substrate that moves and polishes a film to be polished, wherein the CMP abrasive comprises at least the additive for CMP abrasive according to any one of (1) to (13) and a cerium oxide slurry. Polishing method.

  (15) The method for polishing a substrate according to (14), wherein the additive is mixed with the cerium oxide slurry so that the average particle diameter of the cerium oxide particles of the CMP abrasive is 0.1 to 1.0 μm.

  (16) The method for polishing a substrate according to (14) or (15), comprising a step of preparing a CMP abrasive by mixing separately prepared additive for CMP abrasive and cerium oxide slurry immediately before polishing.

  (17) The method for polishing a substrate according to (14) or (15), wherein the CMP abrasive is a mixed liquid in which the additive for CMP abrasive and cerium oxide slurry are mixed in advance.

  (18) A CMP abrasive comprising the CMP abrasive additive according to any one of (1) to (13) and a cerium oxide slurry.

  (19) The CMP abrasive | polishing agent as described in said (18) whose density | concentration of a cerium oxide particle is 0.1-10 mass%.

  (20) The CMP polishing slurry according to the above (18) or (19), wherein the 99% volume component cerium oxide particles among the cerium oxide particles have a particle size in the range of 0.3 μm to 5.0 μm.

  (21) The step of polishing the substrate by the method according to any one of (14) to (17), or polishing the substrate using the CMP abrasive according to any one of (18) to (20) An electronic component manufactured including the process of

  According to the CMP polishing agent and polishing method using the additive for CMP polishing agent of the present invention, high planarization and high uniformity in the wafer surface are possible, and it is suitable for semiconductor element manufacturing processes, particularly for shallow trench isolation. It is. Further, the polished surface of the substrate such as a silicon oxide insulating film can be polished at high speed without being damaged.

  In the present invention, the additive for CMP abrasive is an aqueous solution containing an organic compound having an acetylene bond (carbon-carbon triple bond), a water-soluble vinyl polymer, and water, and having a pH of 4 to 9. By combining with a cerium oxide slurry, it becomes possible to polish an inorganic insulating film such as a semiconductor oxide film as a CMP abrasive.

  The pH of the additive needs to be 4 to 9, preferably 5 to 8, more preferably 5 to 7. An excessively low pH is not preferable because it often causes a sharp decrease in the polishing rate. Further, if the pH is too high, the effect of the additive is small, and the effect of the flattening function is lowered, which is not preferable. The pH can be adjusted by alkali components such as ammonia and tetramethylammonium hydroxide (TMAH) and acids.

The organic compound having an acetylene bond is not particularly limited as long as it contains a carbon-carbon triple bond. Specifically, the organic compound has the general formula (I)

(In general formula (I), R ¹ represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, and R ² represents a substituted or unsubstituted alkyl group having 4 to 10 carbon atoms.) A compound of formula (II)

(In General Formula (II), R ^{3 to} R ⁶ each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, and R ⁷ and R ⁸ each independently represents 1 to 1 carbon atoms. 5 represents a substituted or unsubstituted alkylene group, and m and n each independently represents 0 or a positive number. In general formula (II), m and n are generally represented by average values. Among these compounds, 1-decyne, 5-decyne, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 2,4,7,9-tetramethyl-5-decyne More preferred is -4,7-diol ethoxylate. These may be used alone or in combination of two or more.

  In the present invention, the surface tension of the additive for CMP abrasive is preferably 20 to 60 dyn / cm. . More preferably, it is 20-50 dyn / cm, More preferably, it is 20-40 dyn / cm. If the surface tension is too large, the wettability with respect to the surface to be polished is deteriorated, and there is a possibility that the additive for CMP abrasive does not spread over the entire surface to be polished.

  In the present invention, the water-soluble vinyl polymer is preferably a high molecular polymer selected from polyacrylic acid, polyacrylic acid ammonium salt, polyacrylic acid amine salt, polyvinyl acetate, polyvinylimidazole, and polyvinylpyrrolidone. In addition, polyacrylic acid tetramethylammonium salt, polymethacrylic acid derivatives and the like can be mentioned. These may be used alone or in combination of two or more. Moreover, the copolymer obtained from 2 or more types of monomers may be sufficient.

Moreover, it is preferable that the weight average molecular weights of a vinyl polymer are 100-200,000. More preferably, it is 1,000-20,000, More preferably, it is 1,000-10,000. Particularly preferred is 1,000 to 5,000. The weight molecular weight is a value measured by GPC (gel permeation chromatography) based on polyethylene glycol standard and using ionic water as a solution.

Moreover, in the vinyl polymer mentioned above, it is more preferable that they are polyacrylic acid ammonium salt or polyacrylic acid amine salt.

  In particular, in the present invention, the polyacrylic acid ammonium salt or amine salt is preferably a mixture of a polyacrylic acid ammonium salt or amine salt composed of two types of components having a weight average molecular weight. Specifically, it is composed of two kinds of 100-5,000 polyacrylate ammonium salt or amine salt (A) and 5,000-200,000 polyacrylate ammonium salt or amine salt (B). preferable. The constituent ratio of A and B is preferably such that the constituent weight ratio of A (A / (A + B)) is in the range of 10 to 99%, more preferably 20 to 80%, and still more preferably. It is in the range of 30 to 70%. The amount of adsorption can be controlled by optimizing the ratio of the two components. If the A component of 100 to 5,000 is too much, the adsorbing polyacrylic acid ammonium salt or amine salt may be too thin, and the adsorption effect may be reduced. On the other hand, if the B component of 5,000 to 20,000 is too large, the thickness when adsorbed is sufficient, but unevenness occurs on the adsorption surface, which causes variations in flatness characteristics.

  In the present invention, the molecular weight of the organic compound having an acetylene bond used as an adsorption aid is preferably 100 to 2,000. More preferably, it is 100-1,200, More preferably, it is 400-1,000. If the molecular weight is too large, the number of molecules as the adsorption aid may be reduced, and uniformity in the wafer surface may not be maintained. If the molecular weight is too small, the adsorption aid performance may not be sufficiently exhibited.

  In the present invention, the organic compound having an acetylene bond used as an adsorption aid is preferably contained in the additive in an amount of 0.05 to 5.0% by mass. More preferably, it is 0.1-2.0 mass%, More preferably, it is 0.3-1.0 mass%. If the content is too large, the viscosity tends to increase, the agglomeration of abrasive particles tends to occur, and the polishing characteristics tend to be affected. Moreover, when there is too little content, there exists a tendency for the effect as an adsorption aid to become small.

  In this invention, it is preferable that a vinyl polymer contains 0.05-3.0 mass% in an additive. More preferably, it is 0.1 mass%-2.0 mass%, More preferably, it is 0.3 mass%-1.5 mass%. If the content is too large, viscosity may increase, abrasive particles may aggregate, and polishing characteristics may be affected. Moreover, when there is too little content, it may lead to the result of losing a flat characteristic remarkably.

  In addition to the materials described above, the additive of the present invention may contain a pH adjuster, a solvent other than water, a colorant such as a dye or a pigment, and the like within a range that does not impair the effects of the additive. good.

In the present invention, the additive contains one or more kinds of inorganic anions of SO ₄ ²⁻ , NO ₃ ⁻ , Cl ⁻ , and PO ₄ ³⁻ , and the total concentration thereof is 1 mass ppm to 1000 mass ppm. It is preferable that More preferably, the total concentration is 1 mass ppm to 500 mass ppm, and further preferably 10 mass ppm to 300 mass ppm. When the content is too large, the cerium oxide particles tend to aggregate. Moreover, when there is too little content, it will tend to influence the adsorption | suction characteristic of a vinyl polymer, and will lead to the result of losing flatness characteristic.

In the present invention, it is preferable that the contents of metal cations Na ⁺ , K ⁺ , Fe ³⁺ and Cu ²⁺ contained in the additive are all 1 ppm or less. The metal cations shown above adhere to the semiconductor substrate by direct contact during polishing of the semiconductor substrate, and have the property of sinking into the substrate before being removed by cleaning after adhering. It is preferably 1 ppm or less because it induces deterioration of electrical characteristics by sinking into the surface.

  The additive liquid for abrasives of the present invention can polish an inorganic insulating film for semiconductors as a CMP abrasive by combining with a cerium oxide slurry. That is, the CMP abrasive | polishing agent of this invention contains the said additive for CMP abrasive | polishing agents, and a cerium oxide slurry, It is preferable to mix the additive for CMP abrasive | polishing agents, and a cerium oxide slurry.

  In addition, the polishing method of the present invention is a method in which a substrate on which a film to be polished is formed is pressed against a polishing cloth on a polishing platen and pressed to apply a CMP abrasive containing at least two components of a cerium oxide slurry and the additive of the present invention. While being supplied between the polishing film and the polishing cloth, the film to be polished is polished by relatively moving the substrate and the polishing cloth.

  The mixing method of the additive liquid for abrasive and the cerium oxide slurry is roughly classified into a previous mixing method and a premixing method. In the immediately preceding mixing method, the additive liquid for abrasive and the cerium oxide slurry can be prepared separately, mixed immediately before polishing at the time of polishing, and supplied to a predetermined polishing liquid supply location as a CMP polishing liquid. The predetermined polishing liquid supply location is, for example, on the polishing cloth in the polishing apparatus. Here, as a method of mixing immediately before polishing, for example, a method in which the additive liquid is fed through a separate pipe from the cerium oxide slurry, and these pipes are merged just before the outlet of the supply pipe is mentioned. Alternatively, instead of merging the pipes, there is a method in which the additive liquid for abrasive and the cerium oxide slurry are simultaneously dropped and mixed on the polishing cloth. By arbitrarily changing the composition of the additive solution for abrasive and the cerium oxide slurry, it is possible to adjust the planarization characteristics and the polishing rate. Thus, when mixing by the immediately preceding mixing method, deionized water can be mixed as necessary to adjust the polishing characteristics.

  Further, in the premixing method, separately prepared cerium oxide slurry and additive and, if necessary, deionized water are stored in the state of a mixed solution previously mixed at a predetermined blending ratio, and by using this, The mixed liquid can be supplied by one pipe.

  The cerium oxide slurry mixed with the additive is preferably composed of cerium oxide particles and water, and more preferably contains a dispersant. Examples of the dispersant include ammonium polyacrylate, a copolymer of acrylic amide and ammonium acrylate, and the like.

  When the cerium oxide slurry and the additive are mixed, aggregation of the cerium oxide particles may proceed with time. In the present invention, the additive is preferably mixed with the cerium oxide slurry so that the average particle diameter of the cerium oxide particles of the CMP abrasive is 0.1 to 1.0 μm. More preferably, the average particle size is 0.1 to 0.5 μm, and further preferably 0.1 to 0.3 μm. If the CMP abrasive has an excessively large average particle diameter of cerium oxide particles, it may cause polishing flaws due to the aggregated particles of cerium oxide.

  In order not to generate agglomerated particles having an average particle diameter of cerium oxide exceeding 1.0 μm, the cerium oxide slurry, the additive in the present invention, and if necessary, deionized water are mixed immediately before polishing and polished. There is no problem even if the last mixing method is used. If the average particle size does not exceed 1.0 μm, the cerium oxide slurry, the additive, and deionized water as necessary are mixed in advance and used as a mixed solution during polishing. There is no problem even if the premixing method, which is a supply method, is used.

  Moreover, the CMP abrasive | polishing agent containing the additive for CMP abrasive | polishing agents, and a cerium oxide slurry adjusts the mixing ratio of a cerium oxide slurry and an additive suitably so that the density | concentration of a cerium oxide particle may be 0.1-10 mass%. It is preferable to do. More preferably, the said density | concentration is 0.1-5.0 mass%, More preferably, it adjusts so that it may be 0.2-1.5 mass%. If the concentration of the cerium oxide particles is too low, the polishing rate tends not to be sufficiently obtained. On the other hand, if the concentration of the cerium oxide particles is too high, a sufficient polishing rate can be obtained, but the flatness tends to deteriorate.

  Moreover, it is preferable that the CMP abrasive | polishing agent enters into the range whose particle diameter of the 99% volume component cerium oxide particle is 0.3 micrometer-5.0 micrometers among cerium oxide particles. More preferably, it is 0.4-2.0 micrometers, More preferably, it is 0.4-1.0 micrometers. The 99% volume component is generally referred to as D99. Specifically, when 99% volume component reaches the 99% volume component with respect to all particles by accumulating particles from small particles, it is the largest. The particle size of the particles is shown.

  For the measurement of the average particle diameter and the measurement of D99 shown above, values measured by a laser scattering type particle diameter measuring apparatus are used. For example, a value obtained as a particle size of D50 or D99 with a value measured by a measuring apparatus model number LA-920 manufactured by Horiba, Ltd. can be adopted.

  As a substrate in the polishing method of the present invention, an inorganic insulating film on a semiconductor substrate such as a substrate related to semiconductor element manufacture, for example, a semiconductor substrate at a stage where a circuit element and a wiring pattern are formed, a semiconductor substrate at a stage where a circuit element is formed, etc. A substrate on which is formed. Examples of the film to be polished include the inorganic insulating films such as a silicon oxide film layer, a silicon nitride film layer, and a silicon oxide film layer. By polishing the silicon oxide film layer or silicon nitride film layer formed on such a semiconductor substrate with a CMP abrasive containing the above-mentioned additive and cerium oxide slurry, unevenness on the surface of the silicon oxide film layer is eliminated, and the semiconductor A smooth surface can be formed over the entire surface of the substrate.

  It can also be used for shallow trench isolation. In order to use for shallow trench isolation, the ratio of the silicon oxide film polishing rate to the silicon nitride film polishing rate, and the silicon oxide film polishing rate / silicon nitride film polishing rate is preferably 10 or more. When this ratio is less than 10, the difference between the silicon oxide film polishing rate and the silicon nitride film polishing rate is small, and it becomes difficult to stop polishing at a predetermined position when performing shallow trench isolation. When this ratio is 10 or more, the polishing rate of the silicon nitride film is further reduced and the polishing can be easily stopped, which is preferable for shallow trench isolation. Further, for use in shallow trench isolation, it is preferable that scratches are less likely to occur during polishing.

  Hereinafter, the polishing method will be described by taking as an example the case of a semiconductor substrate on which an inorganic insulating film is formed.

  In the polishing method of the present invention, as a polishing apparatus, a holder for holding a substrate having a film to be polished such as a semiconductor substrate, a motor capable of attaching a polishing cloth (pad), and capable of changing the number of rotations is attached. A general polishing apparatus having a predetermined polishing surface plate can be used. For example, Ebara Manufacturing Co., Ltd. polisher: Model number EPO-111 can be used. As an abrasive cloth, a general nonwoven fabric, a polyurethane foam, a porous fluororesin, etc. can be used, and there is no restriction | limiting in particular. Further, it is preferable that the polishing cloth is grooved so that the CMP abrasive is accumulated. The polishing conditions are not limited, but the rotation speed of the surface plate is preferably low rotation of 200 rpm or less so that the semiconductor substrate does not jump out, and the pressure (working load) applied to the semiconductor substrate is 100 kPa or less so as not to cause scratches after polishing. Is preferred. During polishing, a CMP abrasive is continuously supplied to the polishing cloth with a pump or the like. The supply amount is not limited, but it is preferable that the surface of the polishing pad is always covered with a CMP abrasive.

  The semiconductor substrate after completion of polishing is preferably washed in running water and then dried by removing water droplets adhering to the semiconductor substrate using a spin dryer or the like. By polishing the inorganic insulating film, which is the film to be polished, with the above-described polishing agent in this way, surface irregularities can be eliminated and a smooth surface can be obtained over the entire surface of the semiconductor substrate. After forming the planarized shallow trench in this way, an aluminum wiring is formed on the silicon oxide insulating film layer, and after forming the silicon oxide insulating film again between the wirings and on the wiring by the above method, Polishing is similarly performed using the CMP abrasive to obtain a smooth surface. By repeating this step a predetermined number of times, a semiconductor substrate having a desired number of layers can be manufactured.

  In order to achieve global planarization of a film to be polished (silicon oxide film) having unevenness, it is necessary to selectively polish the protrusions. When the abrasive containing the water-soluble polymer of the present invention is used, a protective film is formed on the surface of the cerium oxide particles or the film to be polished. That is, the film to be polished in the concave portion having a small effective polishing load is protected, but the film to be polished in the convex portion having a large effective polishing load is selectively polished by eliminating the protective film made of the water-soluble polymer, and depends on the pattern. Less global flattening can be achieved.

  As a method for manufacturing the shallow trench structure, the method illustrated in FIG. 1 is common. An example of a manufacturing method will be described with reference to FIG. That is, (1) a shallow trench formed by forming a silicon nitride film 2 on a silicon substrate 1 having a silicon oxide film 1a on the surface, applying a resist film 3 thereon, and performing a photo-sensitive and developing process. Patterning is performed so as to form a structure. (2) Only a portion where the resist film 3 is removed by patterning is dry-etched and removed in the order of silicon nitride 2 to silicon substrate 1 by a dry etching process, and a groove is formed in the silicon substrate 1. Dig in. After the trench is dug, the remaining resist film 3 is removed by ashing, and the substrate is washed so that no foreign matter remains. (3) On the stepped substrate with an excessive film thickness sufficient to completely fill the trench. A silicon oxide film 4 is formed, and (4) CMP polishing is performed with an abrasive in which the additive for CMP abrasive according to the present invention and a cerium oxide slurry are combined.

  Examples of a method for manufacturing an inorganic insulating film to which the additive for CMP abrasive and the polishing method of the present invention are applied include a low-pressure CVD method and a plasma CVD method.

For example, the silicon oxide film formation by the low pressure CVD method uses monosilane: SiH ₄ as the Si source and oxygen: O ₂ as the oxygen source. It can be obtained by performing this SiH ₄ —O ₂ oxidation reaction at a low temperature of 400 ° C. or lower. In some cases, heat treatment is performed at a temperature of 1000 ° C. or lower after CVD. When doping phosphorus: P in order to achieve surface flattening by high-temperature reflow, it is preferable to use a SiH ₄ —O ₂ —PH ₃ reaction gas.

The plasma CVD method has an advantage that a chemical reaction requiring a high temperature can be performed at a low temperature under normal thermal equilibrium. There are two plasma generation methods, capacitive coupling type and inductive coupling type. As a reactive gas, SiH ₄ -N ₂ O gas using SiH ₄ as Si source and N ₂ O as oxygen source and TEOS-O ₂ gas (TEOS-) using tetraethoxysilane (TEOS) as Si source. Plasma CVD method). The substrate temperature is preferably 250 to 400 ° C., and the reaction pressure is preferably 67 to 400 Pa. Thus, the silicon oxide film of the present invention may be doped with elements such as phosphorus and boron. Similarly, in forming the silicon nitride film by the low pressure CVD method, dichlorosilane: SiH ₂ Cl ₂ is used as the Si source, and ammonia: NH ₃ is used as the nitrogen source. The SiH ₂ Cl ₂ —NH ₃ oxidation reaction is performed at a high temperature of 900 ° C.

In the plasma CVD method, examples of the reactive gas include SiH ₄ —NH ₃ -based gas using SiH ₄ as the Si source and NH ₃ as the nitrogen source. The substrate temperature is preferably 300 ° C to 400 ° C.

  In the present invention, the flatness characteristic after CMP polishing is the step height between the convex and concave portions after polishing of a pattern composed of 100 μm / 100 μm line (silicon nitride portion) and space (silicon oxide portion of the groove portion). Can be shown. In the present invention, the above-mentioned pattern after polishing is set to a value calculated by evaluating nine points. The smaller the step, the better the flatness. In general, the step is preferably larger than 0 mm and not more than 500 mm. If the level difference is too large, the flatness deteriorates, and when the multilayer structure is multi-layered, a level difference is generated in the resist, and flatness is preferably required to cause defocusing.

  In the present invention, the uniformity characteristics after CMP polishing can be represented by variations in the thicknesses of the silicon nitride film and the silicon oxide film, respectively, in a number of line and space patterns existing in the polished wafer surface. In the present invention, the above-mentioned pattern after polishing is a value calculated by evaluating nine points in the in-plane X-axis direction. When the film thickness variation in the wafer surface is a silicon nitride film, it is preferably 1 mm to 100 mm, and when it is a silicon oxide film, it is preferably 1 mm to 400 mm. If any film thickness variation is too large, the performance of a large number of devices existing on the wafer surface varies.

The inorganic insulating film that can be polished using the CMP polishing slurry constituted by combining the CMP polishing slurry additive of the present invention and the cerium oxide slurry is not limited to the silicon oxide film formed on the semiconductor substrate, Silicon oxide film formed on a wiring board having wiring, inorganic insulating film such as glass, silicon nitride, film mainly containing polysilicon, Al, Cu, Ti, TiN, W, Ta, TaN, etc., photomask lens・ Optical integrated circuits composed of optical glass such as prisms, inorganic conductive films such as ITO, glass and crystalline materials ・ Optical switching elements / optical waveguides, optical fiber end faces, optical single crystals such as scintillators, solid state laser single crystals Sapphire substrate for blue laser LED, semiconductor single crystal such as SiC, GaP, GaAs, glass substrate for magnetic disk, magnetic head, etc. It is done.

  The present invention also polishes a substrate using the above-described polishing method of the present invention, or a CMP abrasive comprising the CMP abrasive additive of the present invention and a cerium oxide slurry. The present invention relates to an electronic component manufactured including a process. Specific examples of such electronic components include individual semiconductors such as diodes, transistors, compound semiconductors, thermistors, varistors, thyristors, DRAMs (Dynamic Random Access Memory), SRAMs (Static Random Access Memory). Memory devices such as EPROM (Erasable Programmable Read Only Memory), Mask ROM (Mask Read Only Memory), EEPROM (Electrically Eraseable Programmable Read Only Memory), Flash Memory, Microprocessor , DSP, ASIC and other theoretical circuit elements, MMIC (monolithic microwave integrated circuit) and other compound semiconductor integrated circuit elements, hybrid integrated circuits (hybrid IC), Photodiodes, and the like photoelectric conversion element such as a charge coupled device.

  Hereinafter, the present invention will be described in more detail with reference to examples.

(Preparation of additives for CMP abrasives)
Example 1
As shown in Table 1, 10.00 g of 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate (Aldrich reagent, m + n = 3.5) and a weight average molecular weight of 3, 500 ammonium polyacrylate aqueous solution (neutralization degree 20%, 40% aqueous solution) 10.80 g, polyacrylate ammonium salt aqueous solution having a weight average molecular weight of 12,000 (neutralization degree 90%, 40% aqueous solution: pH = 6.1) was mixed with 15.0 g of water and 964.3 g of water, and adjusted to pH = 6.0 with ammonia to obtain an additive for CMP abrasives.

Example 2 to Example 9
A CMP abrasive additive was prepared in the same manner as in Example 1 except that the formulation shown in Table 1 was followed.

  About the additive prepared in Examples 1-9, pH, inorganic anion content, and surface tension were measured, respectively. The measurement results are also shown in Table 1.

(Polishing of insulating film layer and shallow trench isolation layer)
The insulating film layer and the shallow trench isolation layer were polished under the following conditions using the additives prepared in Examples 1 to 9, and the polishing results were measured. Table 2 shows the results.

  The following wafers were used as test wafers for shallow element isolation (STI) insulating film CMP evaluation.

(1) As a blanket wafer with no pattern formed,
(1-a): a wafer (φ200 mm) in which a PE-TEOS silicon oxide film having a thickness of 1000 nm is formed on a Si substrate;
(1-b): A wafer (φ200 mm) in which a silicon nitride film was formed to a thickness of 200 nm on a Si substrate was used.

  (2) As the pattern wafer on which the STI simulation pattern was formed, an international SEMATECH 864 wafer (φ200 mm) having a structure shown in FIG. 2 was used. That is, after forming a silicon nitride film 2 with a film thickness of 150 nm on the silicon substrate 1, the silicon nitride film 2 in the element isolation portion is etched by dry etching, and the exposed silicon substrate 1 is dry-etched with 350 nm to form an element. A wafer in which an isolation structure was formed and an insulating film of the silicon oxide film 4 was formed to a thickness of 600 nm by HDP (High Density Plasma) method was used.

  The test wafer is set in a holder attached with a suction pad for attaching a substrate to be held in a polishing apparatus (product name: Mirara, manufactured by Applied Materials), while a porous urethane resin manufactured by Rodale is mounted on a φ480 mm polishing platen. A polishing pad model number IC-1000 (K groove) was attached. The holder is placed on the pad with the insulating film face down, and the membrane, retainer ring, and inner tube pressure are 3.3 psi, 4.4 psi, 3.3 psi (23.1 kPa, 30.8 kPa, 23.1 kPa).

  A cerium oxide slurry in which 1 wt% of cerium oxide having an average particle size of 0.12 μm was dispersed at a rate of 90 mL / min with each of the additives for CMP abrasives prepared in Examples 1 to 9 on a surface plate was 120 ml / min. The test plate for STI insulating film CMP evaluation was polished by operating the surface plate and the wafer at a rotational speed of 93 / min for 87 minutes while dropping simultaneously at a speed of minutes. The polishing time for blanket wafers (1-a) and (1-b) is 60 seconds, and the polishing time for pattern wafer (2) is 100% (4 × 4 mm convex portion). The silicon nitride film is almost exposed at the pattern portion. The end point of polishing was detected by monitoring the polishing platen torque current value.

  A line-and-space pattern in which the active part masked with silicon nitride, which is a convex part, and the Trench part, in which grooves that are concave parts are formed, are alternately arranged at intervals of 100 μm from the STI simulated pattern The central part of the group (4 × 4 mm area) was evaluated. For the uniformity evaluation, nine line-and-space patterns formed with the convex portion 100 μm width / recess portion 100 μm width shown above were evaluated in the in-plane X-axis direction. Of these nine line-and-space patterns, when the remaining silicon oxide film is 10 nm or more on the silicon nitride film of the active pattern protrusion, additional polishing was performed as needed.

The polished wafer was thoroughly washed with pure water and then dried. Thereafter, by using an optical interference film thickness device (trade name, RE-3000, manufactured by Dainippon Screen Mfg. Co., Ltd.), the remaining film thickness of the recessed insulating film, the remaining film thickness of the protruding insulating film, or the silicon nitride film The remaining film thickness was measured. Furthermore, the remaining level difference of the convex part after a grinding | polishing and a recessed part was measured at 9 points | pieces using the step meter Dektak model number V200-Si by Nippon Beiko. Table 2 shows the measurement results obtained.

Comparative Example 1
As described in Comparative Example 1 in Table 3, 1.5 g of polyvinylpyrrolidone powder was mixed with 998.5 g of pure water, and adjusted to pH = 8.0 with ammonia to prepare an additive for CMP abrasives.

Comparative Example 2 to Comparative Example 4
A CMP abrasive additive was produced in the same manner as in Comparative Example 1 except that the formulation shown in Table 3 was followed.

  About these additives, pH, inorganic anion content, and surface tension were measured, respectively. The results are also shown in Table 3.

(Polishing of insulating film layer and shallow trench isolation layer)
The insulating film layer and the shallow trench isolation layer were polished in the same manner as in Example except that these additives were used, and the polishing results were measured. Table 4 shows the measurement results.

  As shown in Tables 2 and 4, when polishing was performed, in Example 1 to Example 9, the evaluation result of 9 points showed a step average value of 300 mm or less and a maximum value of 450 mm or less. Moreover, the film thickness variation of the silicon nitride film on the convex portion shows a value of 80 mm or less in any of the examples, and the polishing amount of SiN is in the range of 10 mm or more and 90 mm or less, and the autostop property is good. It has been shown. Further, the variation in the thickness of the silicon oxide film in the recesses showed a value of 350 mm or less in any of the examples, and both the silicon oxide film and the silicon nitride film had good uniformity within the wafer surface. Thus, in any of the examples, good flatness and uniformity were exhibited.

  On the other hand, in the case of Comparative Example 1, although the film showed good flatness, the film thickness variation of the silicon nitride film was as large as 125 mm, and there was a problem in uniformity. In the case of the comparative example 2, the variation in the thickness of the silicon oxide film was 520 mm, and the uniformity of the oxide film was not achieved. In the case of Comparative Example 3, although there was no problem with the film thickness variation, the average value of the step was 550 mm, and the flatness was not achieved. In Comparative Example 4, the silicon oxide film and the silicon nitride film had large film thickness variations, and the uniformity of 120 mm and 550 mm respectively did not reach the target.

It is a cross-sectional schematic diagram which shows an example of the manufacturing method of a shallow trench structure. It is a cross-sectional schematic diagram of the pattern wafer used in the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon substrate 1a Silicon oxide film 2 Silicon nitride film 3 Resist film 4 Silicon oxide film

Claims (21)

  It is an aqueous solution containing an organic compound having an acetylene bond, a water-soluble vinyl polymer and water and having a pH of 4 to 9, and it is possible to polish an inorganic insulating film for semiconductors by combining with a cerium oxide slurry for semiconductors. An additive for a CMP abrasive. Organic compounds having an acetylene bond are represented by the general formula (I)

(In general formula (I), R ¹ represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, and R ² represents a substituted or unsubstituted alkyl group having 4 to 10 carbon atoms.) The additive for CMP abrasives of Claim 1 shown by these. The organic compound having an acetylene bond is represented by the general formula (II)

(In General Formula (II), R ^{3 to} R ⁶ each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, and R ⁷ and R ⁸ each independently represents 1 to 1 carbon atoms. 5. A CMP abrasive additive according to claim 1, wherein 5 represents a substituted or unsubstituted alkylene group, and m and n each independently represents 0 or a positive number.   The additive for CMP abrasives according to any one of claims 1 to 3, wherein the surface tension is 20 to 60 dyn / cm.   The vinyl polymer is at least one polymer selected from polyacrylic acid, polyacrylic acid ammonium salt, polyacrylic acid amine salt, polyvinyl acetate, polyvinylimidazole, and polyvinylpyrrolidone. The additive for CMP abrasives as described.   The additive for CMP abrasives according to any one of claims 1 to 5, wherein the vinyl polymer has a weight average molecular weight of 100 to 200,000 (in terms of polyethylene oxide molecular weight).   The additive for CMP abrasives according to any one of claims 1 to 6, wherein the vinyl polymer is a polyacrylic acid ammonium salt or a polyacrylic acid amine salt.   A polyacrylic acid ammonium salt or amine salt is a polyacrylic acid ammonium salt or amine salt having a weight average molecular weight of 1,000 to 5,000 and a polyacrylic acid ammonium salt or amine salt having a weight average molecular weight of 5,000 to 20,000. The additive for CMP abrasives according to claim 7, comprising two kinds of ammonium polyacrylates or amine salts.   The additive for CMP abrasives according to any one of claims 1 to 8, wherein the organic compound having an acetylene bond has a molecular weight of 100 to 20,000.   The additive for CMP abrasives according to any one of claims 1 to 9, wherein the additive contains 0.05 to 5.0% by mass of an organic compound having an acetylene bond.   The additive for CMP abrasives according to any one of claims 1 to 10, wherein the additive contains 0.05 to 3.0% by mass of a vinyl polymer. The inorganic anions SO ₄ ²⁻ , NO ₃ ⁻ , Cl ⁻ and PO ₄ ³⁻ contain one or more kinds, and the total concentration thereof is 1 mass ppm to 1000 mass ppm. Any one additive for CMP abrasive | polishing agent. The additive for CMP abrasives according to any one of claims 1 to 12, wherein the contents of cations Na ⁺ , K ⁺ , Fe ³⁺ and Cu ²⁺ are all 1 ppm or less.   The substrate on which the film to be polished is formed is pressed against the polishing cloth of the polishing platen and pressed, and the substrate and the polishing cloth are moved relative to each other while the CMP abrasive is supplied between the film to be polished and the polishing cloth. A method for polishing a substrate for polishing a polishing film, wherein the CMP abrasive comprises at least an additive for CMP abrasive according to any one of claims 1 to 13 and a cerium oxide slurry.   The method for polishing a substrate according to claim 14, wherein the additive is mixed with the cerium oxide slurry so that the average particle diameter of the cerium oxide particles of the CMP abrasive is 0.1 to 1.0 µm.   16. The method for polishing a substrate according to claim 14 or 15, further comprising a step of preparing a CMP abrasive by mixing a separately prepared additive for CMP abrasive and a cerium oxide slurry immediately before polishing.   The method for polishing a substrate according to claim 14 or 15, wherein the CMP abrasive is a mixed liquid in which a CMP abrasive additive and a cerium oxide slurry are mixed in advance.   A CMP abrasive comprising the additive for CMP abrasive according to claim 1 and a cerium oxide slurry.   The CMP abrasive | polishing agent of Claim 18 whose density | concentration of a cerium oxide particle is 0.1-10 mass%.   The CMP abrasive | polishing agent of Claim 18 or 19 in which the particle size of the 99% volume component cerium oxide particle is contained in the range of 0.3 micrometer-5.0 micrometers among cerium oxide particles.   An electron produced by polishing a substrate by the method according to any one of claims 14 to 17, or polishing the substrate by using the CMP abrasive according to any one of claims 18 to 20. parts.

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