JP2016175949A - CMP polishing liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CMP polishing liquid that can achieve higher polishing speeds and higher dispersion stability while suppressing the occurence of polishing flaws and dishing.SOLUTION: Provided is a CMP polishing liquid of pH 7 or less containing a polishing material, an additive having a functional group whose pKa is in a range of 4 to 9, a particular non-ionic amphiphilic surfactant, and water, and in which the polishing material particle has a core/shell structure composed of a core layer 1 and a shell layer 3, and the core layer 1 contains an oxide of at least one element selected from aluminum, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, indium, tin, yttrium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, tungsten, bismuth, thorium and alkaline earth metals, as well as the shell layer 3 contains cerium oxide.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polishing liquid for CMP. More specifically, the present invention relates to a CMP polishing liquid capable of obtaining a higher polishing rate and dispersion stability while suppressing generation of polishing flaws and dishing.

2. Description of the Related Art In recent years, semiconductor elements (so-called chips) have been improved in degree of integration due to progress in miniaturization of processing technology, and have been formed into multilayer wiring. By adopting such a chip, the storage capacity of a memory device such as a DRAM (Dynamic Random Access Memory) or a flash memory has been dramatically increased.
However, in spite of such improvements in chip integration and multilayer wiring, the size of the chip has increased, and along with miniaturization due to the improvement in integration, the number of steps for manufacturing the chip has increased. For this reason, there is also a problem that the production cost of chips is increasing.

  At present, in order to solve the above-described problems, a processing technique for manufacturing a miniaturized chip having a higher degree of integration is being researched and developed. As one of the processing techniques, a CMP (Chemical Mechanical Polishing) technique using abrasive particles is widely adopted. By adopting this CMP technology, many miniaturization technologies such as planarization of interlayer insulating layers and BPSG layers (silicon oxide insulating layers doped with boron, phosphorus, etc.) are realized in the chip manufacturing process, for example. It was done.

  As such a miniaturization technique, for example, a so-called STI technique, known as Shallow Trench Isolation, is known. In this STI technique, a CMP technique is employed to remove an excess silicon oxide insulating layer formed on the wafer substrate. In this STI technique, in order to stop polishing, a stopper layer having a low polishing rate is formed under the silicon oxide insulating layer. This stopper layer is formed of silicon nitride or the like, and it is desirable that the ratio of the polishing rate of the silicon oxide insulating layer to the polishing rate of the stopper layer is large.

On the other hand, in order to obtain the flatness of the surface to be polished, various abrasives have been studied.
Conventionally, silica particles were generally used as the abrasive particles used in CMP, but the ratio of the polishing rate of the silicon oxide insulating layer to the polishing rate of the stopper layer is small. Large value cerium oxide particles are used.

  For example, in Japanese Patent No. 3335667 and Japanese Patent Laid-Open No. 9-270402, a polishing rate is increased by using an aqueous dispersion using cerium oxide as abrasive particles in a process in which CMP technology is employed in STI technology. And the abrasive | polishing material which can obtain the to-be-polished surface with a comparatively few grinding | polishing damage | wound is disclosed.

  However, in the disclosed method, for example, when over-polishing is performed to remove the polishing residue other than the trench groove, the silicon oxide insulating layer embedded in the trench groove is polished to form a recess or a dent. Due to a phenomenon called “dishing” in which structural defects occur, planarization may be insufficient or electrical performance may deteriorate. The degree of dishing depends on the width of the trench groove, and dishing tends to increase in a wide trench groove.

  In addition, the disclosed cerium oxide particles have excellent polishing characteristics compared to conventional silica particles, but are likely to settle. Further, in order to improve polishing characteristics, if an additive such as a dispersant is added excessively, agglomeration is promoted, and agglomeration and sedimentation are remarkably deteriorated and dispersion stability (durability) is greatly deteriorated.

Japanese Patent No. 3335667 JP-A-9-270402

  The present invention has been made in view of the above-described problems and circumstances, and a solution to the problem is polishing for CMP capable of obtaining higher polishing rate and dispersion stability while suppressing generation of polishing flaws and dishing. Is to provide liquid.

As a result of studying the cause of the above-mentioned problem in order to solve the above-mentioned problems, the present inventor has found that a polishing slurry for CMP containing a specific additive, a nonionic surfactant, and abrasive particles having a core-shell structure Thus, the inventors have found that the above problems can be solved, and have reached the present invention.
That is, the said subject which concerns on this invention is solved by the following means.

1. Non-ion having an abrasive, an additive having a functional group having _a pKa in the range of 4 to 9, a hydrophilic part and a lipophilic part, wherein the hydrophilic part has a number average molecular weight of 500 g / mol or more A polishing slurry for CMP having a pH of 7 or less, comprising a surfactant and water,
The abrasive particles used for the abrasive have a core-shell structure consisting of a core layer and a shell layer,
The core layer is made of aluminum (Al), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), Copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium (Zr), indium (In), tin (Sn), yttrium (Y), gadolinium (Gd), terbium (Tb), From dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), tungsten (W), bismuth (Bi), thorium (Th) and alkaline earth metals Contains an oxide of at least one element selected, and
The CMP polishing liquid, wherein the shell layer contains cerium oxide.

2. The abrasive particles further have an intermediate layer between the core layer and the shell layer; and
The intermediate layer is made of aluminum (Al), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), Copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium (Zr), indium (In), tin (Sn), yttrium (Y), gadolinium (Gd), terbium (Tb), From dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), tungsten (W), bismuth (Bi), thorium (Th) and alkaline earth metals 2. The CMP polishing slurry according to item 1, comprising an oxide of at least one selected element and cerium oxide. Liquid.

By the above means of the present invention, it is possible to provide a CMP polishing liquid capable of obtaining a higher polishing rate and dispersion stability while suppressing generation of polishing flaws and dishing.
The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

  That is, the abrasive can exhibit a high polishing rate by containing cerium in the abrasive particles, but if there is an edge on the surface of the abrasive particles, there is a risk of scratching during polishing. Further, since the hardness is low, the particles are easily broken, and it is necessary to suppress the stress during polishing. As a result, the expected sufficient polishing characteristics cannot be obtained. Therefore, aluminum, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, indium, tin, yttrium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, By using abrasive particles having a core layer containing an oxide of at least one element selected from lutetium, tungsten, bismuth, thorium and alkaline earth metal, and a shell layer containing cerium oxide, It becomes harder to break than cerium oxide particles with respect to the stress applied, and sufficient polishing characteristics can be obtained under appropriate polishing conditions and at a low concentration. That is, it has been found that it is possible to perform precise polishing while maintaining a high polishing rate, and consequently suppress the generation of polishing flaws and dishing.

The schematic diagram which shows the 3 layer structure of the abrasive particle which is one Embodiment which concerns on this invention The graph which shows typically the composition of the 3 layer structure of the abrasive | polishing material particle which is one Embodiment which concerns on this invention The graph which shows typically the composition of the 3 layer structure of the abrasive | polishing material particle which is one Embodiment which concerns on this invention The graph which shows typically the composition of the 2 layer structure of the abrasive | polishing material particle which is one Embodiment which concerns on this invention The graph which shows typically the composition of the 2 layer structure of the abrasive | polishing material particle which is one Embodiment which concerns on this invention

The polishing slurry for CMP of the present invention has an abrasive, an additive having a functional group having _a pKa in the range of 4 to 9, a hydrophilic portion and a lipophilic portion, and the hydrophilic portion is 500 g / mol. A polishing slurry for CMP having a pH of 7 or less, comprising a nonionic surfactant having the above number average molecular weight and water,
The abrasive particles used for the abrasive have a core-shell structure consisting of a core layer and a shell layer,
The core layer contains an oxide of the specific element, and
The shell layer contains cerium oxide. This feature is a technical feature common to the inventions according to claims 1 and 2. Thereby, this invention can obtain a higher polishing rate and dispersion stability, suppressing generation | occurrence | production of a polishing flaw and dishing.

Furthermore, in the present invention, the abrasive particles further have an intermediate layer between the core layer and the shell layer, and
The intermediate layer preferably contains the oxide of the specific element and cerium oxide.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.
Further, in the following description, “inner side” means the center side of the abrasive particles, and “outer side” means the opposite side of the “inner side” (outer direction of the core layer).
Further, the “particle diameter” will be described as representing the diameter of a sphere.

(Outline of polishing liquid for CMP of the present invention)
The polishing slurry for CMP of the present invention has an abrasive, an additive having a functional group having _a pKa in the range of 4 to 9, a hydrophilic portion and a lipophilic portion, and the hydrophilic portion is 500 g / mol. A polishing slurry for CMP having a pH of 7 or less, comprising a nonionic surfactant having the above number average molecular weight and water,
The abrasive particles used for the abrasive have a core layer and a shell layer.

<Abrasive>
Common abrasives include those made by dispersing abrasive particles such as bengara (αFe ₂ O ₃ ), cerium oxide, aluminum oxide, manganese oxide, zirconium oxide, colloidal silica in water or oil to form a slurry. is there. In the polishing process of a semiconductor device or glass, the present invention performs polishing with both physical action and chemical action in order to obtain a sufficient polishing rate while suppressing generation of polishing flaws and dishing. The present invention relates to a polishing slurry for CMP containing an abrasive in which abrasive particles having a core layer and a shell layer and capable of mechanical polishing (CMP) are used, and the details thereof will be described below.

<Abrasive particles>
The abrasive particles according to the present invention preferably have a structure of two or more layers having at least a core layer and a shell layer, and the core layer includes aluminum (Al), scandium (Sc), titanium (Ti), vanadium (V), Chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium (Zr), Indium (In), tin (Sn), yttrium (Y), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), At least one selected from lutetium (Lu), tungsten (W), bismuth (Bi), thorium (Th) and alkaline earth metal By weight of oxides of elements, and,
The shell layer contains cerium oxide.

  Particularly preferred are abrasive particles having a three-layer structure having a core layer 1, an intermediate layer 2, and a shell layer 3.

  The intermediate layer is made of aluminum (Al), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium (Zr), indium (In), tin (Sn), yttrium (Y), gadolinium (Gd), terbium (Tb), dysprosium Selected from (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), tungsten (W), bismuth (Bi), thorium (Th) and alkaline earth metals At least one elemental oxide as well as cerium oxide.

  Specifically, as shown in FIG. 1, the abrasive particles having a three-layer structure include a core layer 1 mainly composed of yttrium oxide, and an intermediate containing yttrium oxide and cerium oxide formed outside the core layer 1. A layer 2 and a shell layer 3 mainly composed of cerium oxide formed outside the intermediate layer 2 are provided. For example, the core layer 1 of the abrasive particle A having a three-layer structure shown in FIG. 2A contains almost no cerium oxide and is mainly composed of yttrium oxide. Specifically, it may be less than or equal to the ratio of cerium oxide contained in the intermediate layer 2 formed outside the core layer 1. In the intermediate layer 2, the cerium oxide content changes (decreases) in composition at a constant concentration gradient from the outside of the intermediate layer 2 to the inside of the intermediate layer 2. In addition, the ratio of the cerium oxide contained in the intermediate | middle layer 2 should just be more than the ratio of the cerium oxide contained in the core layer 1, and below the ratio of the cerium oxide contained in the shell layer 3. The shell layer 3 formed outside the intermediate layer 2 contains cerium oxide at a ratio of approximately 100 mol%. Specifically, the ratio of cerium oxide contained in the shell layer 3 is preferably in the range of 50 to 100 mol%, and particularly preferably 75 mol% or more. This is because the excellent polishing rate of cerium oxide can be exhibited by bringing the concentration of cerium oxide contained in the shell layer 3 that becomes the surface of the abrasive particles A close to 100 mol%. The abrasive particles A having a three-layer structure may have a three-layer structure as shown in FIG. 2B. That is, the ratio of yttrium oxide and cerium oxide contained in the intermediate layer 2 may be constant regardless of the distance from the center of the abrasive particle A, and may be approximately half each.

  Alternatively, the abrasive particles A may include two layers in which the core layer 1 and the intermediate layer 2 substantially form one layer (composite layer) and the shell layer 3 is mainly composed of cerium oxide. For example, as shown in FIG. 2C, the core layer 1 and the intermediate layer 2 may have a structure that is not distinguished. That is, the abrasive particles A are mainly composed of the core layer 1 that has no boundary with the intermediate layer 2 and has approximately half the content of yttrium oxide and cerium oxide, and cerium oxide formed outside the core layer 1. The structure comprised from the shell layer 3 to be used may be sufficient. In addition, the layer (composite layer) which is substantially one layer formed by the core layer 1 and the intermediate layer 2 may contain cerium oxide with a predetermined concentration gradient. Specifically, as shown in FIG. 2D, a structure in which the composition changes (decreases) with a constant concentration gradient from the shell layer 3 side to the center side of the abrasive particles A may be employed. In addition, although the oxide contained in the abrasive particles A has been described as an example of an oxide containing yttrium oxide that is not easily broken against stress applied when used, it is not limited thereto, and aluminum, Scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, indium, tin, yttrium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, tungsten, Preference is given to oxides of at least one element selected from bismuth, thorium or alkaline earth metals. The elements contained as the main component in the core layer 1 of the abrasive particles A are aluminum, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, indium, An oxide of at least one element selected from tin, yttrium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, tungsten, bismuth, thorium, or an alkaline earth metal is preferable, and the intermediate layer 2 Although it is preferable to maintain the same bonding strength between the layers as the oxide of the contained element, it is not limited to this. For example, the aluminum, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, indium, tin, yttrium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium The oxide of at least one element selected from lutetium, tungsten, bismuth, thorium, or alkaline earth metal may be an oxide of an element different between the core layer 1 and the intermediate layer 2.

<Method for producing abrasive particles>
Although the manufacturing method of the abrasive particle A having a three-layer structure is shown below as the manufacturing method of the abrasive particle A, it is an example and is not limited to this, and the core layer 1 and the intermediate layer 2 A two-layer structure without distinction or a core-shell two-layer structure without the intermediate layer 2 may be used.
The method for producing abrasive particles A in the present invention generally comprises the following five steps.

1. Core layer precursor forming step The core layer precursor forming step is first performed by aluminum, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, indium, tin, yttrium, Adding a urea compound to an aqueous solution containing a salt of at least one element selected from gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, tungsten, bismuth, thorium or an alkaline earth metal, Aluminum, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, indium, tin, yttrium, gadolinium, terbium, dysprosium A first dispersion solution is prepared in which a basic carbonate of at least one element selected from sodium, holmium, erbium, thulium, ytterbium, lutetium, tungsten, bismuth, thorium, or an alkaline earth metal is dispersed. The aluminum, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, indium, tin, yttrium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium As the salt of at least one element selected from lutetium, tungsten, bismuth, thorium or alkaline earth metal, nitrates, hydrochlorides, sulfates and the like can be used, but nitrates are preferably used. As urea compounds, urea, urea salts (eg, nitrates, hydrochlorides, etc.), N, N′-dimethylacetylurea, N, N′-dibenzoylurea, benzenesulfonylurea, p-toluenesulfonylurea, trimethyl Urea, tetraethylurea, tetramethylurea, triphenylurea, tetraphenylurea, N-benzoylurea, methylisourea, ethylisourea and the like can be mentioned, and urea is preferred. In the following examples, the core layer precursor formation step is shown as an example in which a basic carbonate is formed using urea, but is not limited thereto.

Aluminum, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, indium, tin, yttrium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, The ion concentration in the aqueous solution of at least one element selected from tungsten, bismuth, thorium or alkaline earth metal is 0.001 mol / L to 0.1 mol / L, and urea is 5 to 50 times the ion concentration. Is preferred. This is aluminum, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, indium, tin, yttrium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, A spherical shape that exhibits monodispersity by setting the ion concentration in an aqueous solution and the ion concentration of urea in an aqueous solution of at least one element selected from ytterbium, lutetium, tungsten, bismuth, thorium, or an alkaline earth metal within this range. This is because the abrasive particles A can be synthesized.
The mixed aqueous solution is heated and stirred at 80 ° C. or higher to grow a basic carbonate serving as a core layer precursor dispersed in the aqueous solution (hereinafter referred to as a first dispersion solution).
In the case of heating and stirring, the shape of the stirrer is not particularly specified if sufficient stirring efficiency can be obtained, but in order to obtain higher stirring efficiency, a rotor / stator type stirrer should be used. Is preferred.

2. Intermediate layer precursor forming step The intermediate layer precursor forming step is performed by adding aluminum, scandium, titanium, vanadium, chromium, manganese, iron, the first dispersion solution containing the basic carbonate formed by the core layer precursor forming step. Selected from cobalt, nickel, copper, zinc, gallium, germanium, zirconium, indium, tin, yttrium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, tungsten, bismuth, thorium or alkaline earth metals, An aqueous solution containing a salt of an element contained in the core layer precursor forming step, for example, yttrium nitrate and an aqueous solution containing a cerium (Ce) salt are added. Then, for example, by forming an intermediate layer precursor in which yttrium and cerium are mixed on the outside of the basic carbonate of yttrium that is the core layer precursor, the core layer precursor is grown to form a base having a larger particle diameter. Water carbonate is obtained. Specifically, the addition rate of the aqueous solution added to the first dispersion solution is preferably within a range of 0.003 to 3.0 mmol / min per liter of the first dispersion solution, and in particular, cerium (Ce) occupying the added amount. The proportion is preferably less than 90 mol%. This is because if the rate of cerium (Ce) occupying the addition rate and the addition amount is out of the range, it is difficult for the abrasive particles A to be formed to be spherical particles exhibiting monodispersity. The first dispersion solution is preferably heated and stirred at 80 ° C. or higher while the aqueous solution is added at the above rate. This is because when heated and stirred at 80 ° C. or lower, decomposition of urea added in the core layer precursor forming step does not proceed and particle formation is inhibited. Here, the dispersion solution in which the particles in which the intermediate layer precursor is formed outside the core layer precursor is dispersed is referred to as a second dispersion solution.

3. Shell Layer Precursor Forming Step The shell layer precursor forming step includes cerium (Ce) in the second dispersion solution in which the particles having the intermediate layer precursor formed on the outside of the core layer precursor by the intermediate layer precursor forming step are dispersed. By adding an aqueous solution containing the above salt, a shell layer precursor containing cerium (Ce) basic carbonate as a main component is formed outside the intermediate layer precursor to further grow the particles. The aqueous solution containing a salt of cerium (Ce) is preferably added while heating and stirring at 80 ° C. or higher at an addition rate within a range of 0.003 to 3.0 mmol / min per liter of the aqueous solution. This is because if the addition rate is out of the range, it is difficult for the abrasive particles A to be formed to be spherical particles exhibiting monodispersity. As for the heating temperature, as in the case of the intermediate layer precursor forming step, when heated and stirred at 80 ° C. or lower, decomposition of urea added in the core layer precursor forming step does not proceed and particle formation is inhibited. It is. Here, the dispersion solution in which the particles in which the shell layer precursor is formed outside the intermediate layer precursor is dispersed is referred to as a third dispersion solution.

4). Solid-liquid separation step The solid-liquid separation step recovers the solid in which the shell layer precursor is formed outside the intermediate layer precursor from the third dispersion obtained in the shell layer precursor formation step by the operation of solid-liquid separation. To obtain an abrasive precursor. In the solid-liquid separation step, the abrasive precursor obtained as necessary may be dried and then transferred to the firing step.

5. Firing step In the firing step, the basic carbonate abrasive precursor obtained by solid-liquid separation is fired at 400 ° C. or higher in air or in an oxidizing atmosphere. The baked abrasive precursor becomes an oxide, and becomes an abrasive particle A whose outer side is covered with cerium oxide.

<Abrasive particle size, polishing speed, surface accuracy>
The abrasive particles A have different required levels for the particle diameter depending on their use, but as the finished surface accuracy after polishing such as reduction of polishing scratches and improvement of flatness becomes higher, polishing contained in the abrasive used. The material particles A need to be finely divided. For example, the average particle size needs to be 2.0 μm or less for use in the manufacturing process of a semiconductor device. The smaller the particle size of the abrasive, the higher the finished surface accuracy after polishing. On the other hand, the smaller the particle size, the slower the polishing rate. The superiority that the polishing rate of the material is faster than that of an abrasive such as colloidal silica is lost. Therefore, the average particle diameter of the abrasive particles A is preferably in the range of 0.02 to 2.0 μm, and more preferably in the range of 0.05 to 1.5 μm.
Further, in order to increase the planar accuracy after the polishing process, it is necessary to use abrasive particles A that have the same particle diameter as much as possible and have a small particle diameter distribution coefficient of variation (hereinafter also simply referred to as “variation coefficient”). desirable.
Further, it is preferable that the coefficient of variation of the abrasive particles A is small, since it does not include abrasive particles having a particle size significantly larger than the average that promotes aggregation, and dispersion stability is improved.

<Abrasive slurry>
The abrasive slurry in the present invention is obtained, for example, by dispersing a composition comprising abrasive particles A having the above characteristics, a dispersant for the abrasive particles A in water and water. Here, although there is no restriction | limiting in content of abrasive particle A, the inside of the range of 0.1-40 mass% is preferable from the ease of handling of a dispersion liquid, and the inside of the range of 0.5-20 mass% is more preferable. When this concentration is 0.1% by mass or more, it is possible to avoid a possibility that the polishing rate is lowered, and when it is 40% by mass or less, it is possible to avoid a possibility that the abrasive particles A are aggregated. Further, the content of the abrasive particles A in the CMP polishing liquid when the abrasive slurry and the additive liquid are mixed is preferably in the range of 0.01 to 10% by mass, and in the range of 0.1 to 5% by mass. The inside is more preferable.

<Additive having a functional group in the range of _pK a 4 to 9>
The additive contained in the CMP polishing liquid in the present invention accepts the surface more for interaction with the abrasive particles A, and in order to modify the surface characteristics of the silicon-containing dielectric layer being polished. It is included in the polishing liquid.
The pH of the CMP polishing liquid plays an important role in determining the interaction between the additive and the surface of the silicon-containing dielectric layer. The CMP polishing liquid of the present invention has a pH of 7 or less, preferably 6.5 or less (for example, 5.5 or less) at a liquid temperature of 25 ° C. The CMP polishing liquid typically has a pH of at least 2, preferably at least 3 (eg, at least 3.5).

In order for the additive to interact with the silicon-containing dielectric layer within this pH range, the additive should be in the range of 4-9, preferably in the range of 4-7 (eg 4-6) at a liquid temperature of 25 ° C. It is desirable to retain a functional group having an inner pK _a (in water). Furthermore, it is desirable for the additive to have an overall net charge that is more positive than about −1 (eg, net charge = 0, +1, +2, etc.). The net charge is determined to be the charge of the additive when a functional group having _a pKa in the range of 4-9 is protonated.

The functional group of the additive may be any suitable functional group and is typically an amine, carboxylic acid, alcohol, thiol, sulfonamide, imide, hydroxamic acid, barbituric acid, hydrazine, amidoxime. ), Their salts and combinations thereof. Retain these functional groups, the additive having a pK _a in the range of 4 to 9, arylamine, amino alcohols, aliphatic amines, heterocyclic amines, hydroxamic acids, aminocarboxylic acids, cyclic monocarboxylic acids , One or more compounds selected from the group consisting of unsaturated monocarboxylic acids, substituted phenols, sulfonamides, thiols and combinations thereof. Preferably, the additive comprises one or more compounds selected from the group consisting of arylamines, heterocyclic amines, aminocarboxylic acids and combinations thereof. All of the aforementioned additives are salts such as hydrochloride, hydrobromide salt, sulfate, sulfonate, trifluoromethanesulfonate, acetate, trifluoroacetate, picrate, perfluorobutyrate, sodium salt, The salt may be present in the form of a salt selected from the group consisting of potassium salt, ammonium salt, halide salt and the like.

The arylamine can be any suitable arylamine having _a pKa in the range of 4-9. Preferably, the arylamine is a primary arylamine. The arylamine is a group consisting of _C1-12 alkyl, _C1-12 alkoxy, _C6-12 aryl, carboxylic acid, sulfonic acid, phosphonic acid, hydroxyl, thiol, sulfonamide, acetamide, salts thereof and combinations thereof Optionally substituted with one or more substituents selected from For example, arylamine includes aniline, 4-chloroaniline, 3-methoxyaniline, N-methylaniline, 4-methoxyaniline, p-toluidine, anthranilic acid, 3-amino-4-hydroxybenzenesulfonic acid, aminobenzyl alcohol, Aminobenzylamine, 1- (2-aminophenyl) pyrrole, 1- (3-aminophenyl) ethanol, 2-aminophenyl ether, 2,5-bis- (4-aminophenyl) -1,3,4-oxa Diazole, 2- (2-aminophenyl) -1H-1,3,4-triazole, 2-aminophenol, 3-aminophenol, 4-aminophenol, dimethylaminophenol, 2-aminothiolphenol, 3-amino Thiolphenol, 4-aminothiolphenol, 4-amino Phenylmethyl sulfide, 2-aminobenzenesulfonamide, orthonilic acid, 3-aminobenzeneboronic acid, 5-aminoisophthalic acid, sulfacetamide, sulfanilic acid, o-arsanilic acid, p-arsanilic acid, (3R) -3- (4 -Trifluoromethylphenylamino) pentanoic acid amides, their salts and combinations thereof.

The amino alcohol can be any suitable amino alcohol having _a pKa in the range of 4-9. For example, the amino alcohol may be selected from the group consisting of triethanolamine, benzyldiethanolamine, tris (hydroxymethyl) aminomethane, hydroxylamine, tetracycline, salts thereof, and combinations thereof. Preferably, the amino alcohol is a tertiary amino alcohol.

The aliphatic amine can be any suitable aliphatic amine having _a pKa in the range of 4-9. Suitable aliphatic amines include methoxyamine, hydroxylamine, N-methylhydroxylamine, N, O-dimethylhydroxylamine, β-difluoroethylamine, ethylenediamine, triethylenediamine, diethylbutylamino- (2-hydroxyphenyl) methyl) Phosphonate, iminoethane, iminobutane, triallylamine, cyanoamine (eg, aminoacetonitrile, diethylaminoacetonitrile, 2-amino-2-cyanopropane, (isopropylamino) propionitrile, (diethylamino) propionitrile, aminopropionitrile, dicyanodiethylamine , 3- (dimethylamino) propionitrile, salts thereof, and combinations thereof, and the aliphatic amine may be hydrazine. Preferably, hydrazine is hydrazine, methyl hydrazine, tetramethyl hydrazine, N, N-diethyl hydrazine, phenyl hydrazine, N, N-dimethyl hydrazine, trimethyl hydrazine, ethyl hydrazine, salts thereof (for example, hydrochloride) and the like. One or more compounds selected from the group consisting of:

The heterocyclic amine may be any suitable heterocyclic amine having _a pKa in the range of 4-9, including monocyclic, bicyclic and tricyclic amines. Typically, the cyclic amine is a 3-, 4-, 5-, or 6-containing one or more nitrogen atoms and one or more other atoms such as carbon, carbon and oxygen, and carbon and sulfur. It is a membered cyclic structure. Preferably, the cyclic amine is a 5 or 6 membered cyclic structure. Heterocyclic _{amines, H, OH, COOH, SO} 3 H, PO 3 H, Br, Cl, OH I, F, NO 2, _hydrazine, a _{C 1 to 8} alkyl (optionally, COOH, Br, Cl, I Or substituted with NO ₂ ), C _6-12 aryl (optionally substituted with OH, COOH, Br, I or NO ₂ ), C (O) H, C (O) R (where R Is optionally substituted with one or more substituents selected from the group consisting of C _1-8 alkyl or C _6-12 aryl) and C _1-8 alkenyl. Desirably, the heterocyclic amine contains at least one unsubstituted heterocyclic nitrogen. For example, heterocyclic amines include imidazole, 1-methylimidazole, 2-methylimidazole, 2-ethylimidazole, 2-hydroxymethylimidazole, 1-methyl-2-hydroxymethylimidazole, benzimidazole, quinoline, isoquinoline, hydroxyquinoline. , Melamine, pyridine, bipyridine, 2-methylpyridine, 4-methylpyridine, 2-aminopyridine, 3-aminopyridine, 2,3-pyridinedicarboxylic acid, 2,5-pyridinedicarboxylic acid, 2,6-pyridinedicarboxylic acid 5-butyl-2-pyridinecarboxylic acid, 4-hydroxy-2-pyridinecarboxylic acid, 3-hydroxy-2-pyridinecarboxylic acid, 2-pyridinecarboxylic acid, 3-benzoyl-2-pyridinecarboxylic acid, 6-methyl -2-pyridinecal Acid, 3-methyl-2-pyridinecarboxylic acid, 6-bromo-2-pyridinecarboxylic acid, 6-chloro-2-pyridinecarboxylic acid, 3,6-dichloro-2-pyridinecarboxylic acid, 4-hydrazino-3 , 5,6-trichloro-2-pyridinecarboxylic acid, quinoline, isoquinoline, 2-quinolinecarboxylic acid, 4-methoxy-2-quinolinecarboxylic acid, 8-hydroxy-2-quinolinecarboxylic acid, 4,8-dihydroxy-2 -Quinolinecarboxylic acid, 7-chloro-4-hydroxy-2-quinolinecarboxylic acid, 5,7-dichloro-4-hydroxy-2-quinolinecarboxylic acid, 5-nitro-2-quinolinecarboxylic acid, 1-isoquinolinecarboxylic acid , 3-isoquinolinecarboxylic acid, acridine, benzoquinoline, benzoacridine, clonidine, anabasine, Mycotine, triazolopyridine, pyridoxine, serotonin, histamine, benzodiazepine, aziridine, morpholine, 1,8-diazabicyclo [5,4,0] undecene-7 (DABCO), hexamethylenetetramine, piperazine, N-benzoylpiperazine 1-tosylpiperazine, N-carboethoxypiperazine, 1,2,3-triazole, 1,2,4-triazole, 2-aminothiazole, pyrrole, pyrrole-2-carboxylic acid and its alkyl, halo or carboxylic acid substitutions Derivatives, 3-pyrroline-2-carboxylic acid, ethylpyrroline, benzylpyrroline, cyclohexylpyrroline, tolylpyrroline, tetrazole, 5-cyclopropyltetrazole, 5-methyltetrazole, 5-hydroxytetrazole It may be sol, 5-phenoxytetrazole, 5-phenyltetrazole, salts thereof, and combinations thereof. The heterocyclic amine may also be an imide, an aminidine or a barbituric acid compound. For example, suitable imides include fluorouracil, methylthiouracil, 5,5-diphenylhydantoin, 5,5-dimethyl-2,4-oxazolidinedione, phthalimide, succinimide, 3,3-methylphenylglutarimide, 3,3- Dimethyl succinimide, their salts and combinations thereof are included. Suitable aminidins include imidazo [2,3-b] thioxazole, hydroxyimidoazo [2,3-a] isoindole, their salts and combinations thereof. Suitable barbituric acids include 5,5-methylphenyl barbituric acid, 1,5,5-trimethylbarbituric acid, hexobarbital, 5,5-dimethylbarbituric acid, 1,5-dimethyl-5- Phenyl barbituric acid, their salts and combinations thereof are included.

The hydroxamic acid can be any suitable hydroxamic acid having _a pKa in the range of 4-9. Suitable hydroxamic acids include formohydroxamic acid, acetohydroxamic acid, benzohydroxamic acid, salicylhydroxamic acid, 2-aminobenzohydroxamic acid, 2-chlorobenzohydroxamic acid, 2-fluorobenzohydroxamic acid, 2-fluoro Nitrobenzohydroxamic acid, 3-nitrobenzohydroxamic acid, 4-aminobenzohydroxamic acid, 4-chlorobenzohydroxamic acid, 4-fluorobenzohydroxamic acid, 4-nitrobenzohydroxamic acid, 4-hydroxybenzohydroxamic acid, salts thereof And combinations thereof.

The aminocarboxylic acid can be any suitable aminocarboxylic acid having _a pKa in the range of 4-9. Proline, common amino acid compounds of such glycine and phenylglycine for carboxylic acid moieties have a pK _a in the range of 9-10 for range and amino moieties of 2 to 2.5, the Not suitable for use in the context of the invention. In contrast, aminocarboxylic acids such as glutamic acid, beta-hydroxyglutamic acid, aspartic acid, asparagine, azaserine, cysteine, histidine, 3-methylhistidine, cytosine, 7-aminocephalosporanic acid and camosine are each 4 to It contains functional groups with _a pKa in the range of 9.

The cyclic monocarboxylic acid can be any suitable cyclic monocarboxylic acid having _a pKa in the range of 4-9. Dicarboxylic acids and polycarboxylic acids can be used for polishing has been suggested previously a silicon-containing dielectric layer may have a pK _a of the desired range, undesirable agglomeration of the inorganic abrasive, the adhesive or rapid precipitation It has a total charge associated with it. Desirably, the cyclic carboxylic acid compound comprises a _C4-12 cyclic alkyl or _C6-12 aryl group. Cyclic carboxylic acid compound, H, OH, COOH, Br , Cl, I, F, NO 2, _hydrazine, a _{C 1 to 8} alkyl (optionally OH, COOH, Br, Cl, substituted with I or NO ₂ C _6-12 aryl (optionally substituted with OH, COOH, Br, I or NO ₂ ), C (O) H, C (O) R (where R is C _1-8 alkyl). Or C _6-12 aryl) and optionally substituted by one or more substituents selected from the group consisting of C _1-8 alkenyl. Preferably, the cyclic carboxylic acid compound is not dihydroxybenzoic acid or polyhydroxybenzoic acid. Suitable cyclic monocarboxylic acid compounds include benzoic acid, C _1-12 alkyl substituted benzoic acid, C _1-12 alkoxy substituted benzoic acid, naphthalene 2-carboxylic acid, cyclohexane carboxylic acid, cyclohexyl acetic acid, 2-phenyl acetic acid, 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 2-piperidinecarboxylic acid, cyclopropanecarboxylic acid (eg cis- and trans-2-methylcyclopropanecarboxylic acid), their salts and combinations thereof are included. Particularly preferred polishing additives are 4-hydroxybenzoic acid, cyclohexanecarboxylic acid, benzoic acid, their salts and combinations thereof.

The unsaturated monocarboxylic acid can be any suitable unsaturated monocarboxylic acid (eg, alkene carboxylic acid) having _a pKa in the range of 4-9. Typically, the unsaturated monocarboxylic acid is a C _3-6 alk-2-enoic acid. Preferably, the unsaturated monocarboxylic acid is cinnamic acid, propenoic acid (eg acrylic acid, 3-chloroprop-2-enecarboxylic acid), butenoic acid (eg crotonic acid, 3-chlorobut-2-enecarboxylic acid). 4-chlorobut-2-enecarboxylic acid), pentenoic acid (eg cis- or trans-2-pentenoic acid, 2-methyl-2-pentenoic acid), hexenoic acid (eg 2-hexenoic acid, 3-ethyl- 2-hexenoic acid), their salts and combinations thereof.

The substituted phenol can be any suitable substituted phenol having _a pKa in the range of 4-9. Preferably, the substituted phenol contains a substituent selected from nitro, chloro, bromo, fluoro, cyano, alkoxycarbonyl, alkanoyl, acyl, alkylsulfonyl and combinations thereof. Suitable nitrophenols include nitrophenol, 2,6-dihalo-4-nitrophenol, 2,6-di- _C1-12 alkyl-4-nitrophenol, 2,4-dinitrophenol, 2,6-dinitro. Trinitrophenol such as phenol, 3,4-dinitrophenol, 2- _C1-12 alkyl-4,6-dinitrophenol, 2-halo-4,6-dinitrophenol, dinitro-o-cresol, picric acid, etc. And salts thereof.

The sulfonamide can be any suitable sulfonamide having _a pKa in the range of 4-9. Suitable sulfonamides include N-chlorotolylsulfonamide, dichlorophenamide, mafenide, nimesulide, sulfamethizole, sulfaperine, sulfacetamide, sulfadiazine, sulfadimethoxine, sulfamethazine, sulfapyridine, sulfaquinoxaline, salts thereof and the like Is included.

The thiol can be any suitable thiol having _a pKa in the range of 4-9. Suitable thiols include hydrogen sulfide, cysteamine, cysteinyl cysteine, methsteine, thiophenol, p-chlorothiophenol, o-aminothiophenol, o-mercaptophenylacetic acid, p-nitrobenzenethiol, 2 -Mercaptoethanesulfonate, N-dimethylcysteamine, dipropylcysteamine, diethylcysteamine, mercaptoethylmorpholine, methylthioglycolate, mercaptoethylamine, N-trimethylcysteine, glutathione, mercaptoethylpiperidine, diethylaminopropanethiol, salts thereof And combinations thereof.

  When the additive is an arylamine, the additive preferably comprises one or more compounds selected from the group consisting of aniline, anthranilic acid, aminophenol, alternic acid, salts thereof and combinations thereof. When the additive is a heterocyclic amine compound, the additive is preferably imidazole, quinoline, pyridine, 2-methylpyridine, 2-pyridinecarboxylic acid, pyridinedicarboxylic acid, 2-quinolinecarboxylic acid, morpholine, piperazine, It includes one or more compounds selected from the group consisting of triazole, pyrrole, pyrrole-2-carboxylic acid, tetrazole, salts thereof, and combinations thereof. When the additive is an aminocarboxylic acid compound, the additive preferably comprises one or more compounds selected from the group consisting of glutamic acid, aspartic acid, cysteine, histidine, salts thereof, and combinations thereof. When the additive is a cyclic monocarboxylic acid compound, the additive is preferably selected from the group consisting of benzoic acid, cyclohexanecarboxylic acid, cyclohexylacetic acid, 2-phenylacetic acid, their salts, and combinations thereof. One or more compounds.

  The polishing liquid for CMP typically contains 5% by mass or less of an additive (for example, 2% by mass or less of a polishing additive). The CMP polishing liquid typically contains 0.005% by mass or more of an additive (for example, 0.01% by mass or more of a polishing additive). Preferably, the CMP polishing liquid contains 1% by mass or less (for example, 0.5% by mass or less or 0.2% by mass or less) of an additive. Preferably, the additive is an arylamine, amino alcohol, aliphatic amine, heterocyclic amine, hydroxamic acid, aminocarboxylic acid, cyclic monocarboxylic acid, unsaturated monocarboxylic acid, substituted phenol, sulfonamide, thiol, they Or one or more compounds selected from the group consisting of combinations thereof.

(Nonionic surfactant)
The hydrophilic part of the surfactant is highly substituted with oxyethylene (—O—CH ₂ —CH ₂ —) repeating units, vinyl alcohol [—CH ₂ —CH ₂ (OH) —] repeating units, sorbitan groups. _Contains, consists essentially of or consists of saturated or partially unsaturated _C6-30 alkyl or combinations thereof (e.g., polyoxyethylene sorbitan). The highly substituted saturated or partially unsaturated _C6-30 alkyl is preferably substituted with one or more hydrophilic functional groups, such as hydroxy groups. The hydrophilic portion of the nonionic surfactant typically has a molecular weight of at least 500 g / mol (eg, 1000 g / mol or more, 1500 g / mol or more, or 3000 g / mol or more). When a nonionic surfactant having a number average molecular weight exceeding 500 g / mol is used together with the abrasive particles in the present invention, dishing can be remarkably reduced, which is preferable.
In the case of a polymeric or oligomeric hydrophilic substance, the molecular weight is preferably a number average molecular weight. A compound having a very high number average molecular weight may result in an increase in viscosity that is detrimental to slurry handling, polishing performance and slurry stability. Accordingly, it is preferable to use a surfactant having a hydrophilic portion having a number average molecular weight of less than 1000000 g / mol (that is, less than 100000 g / mol, less than 50000 g / mol or less than 10000 g / mol).

  The lipophilic portion of the surfactant may be a silicon-free fragment that contains a hydrocarbon portion in which there are 6-30 hydrocarbon units (eg, 10-20 hydrocarbon units). Preferably, the hydrocarbon moiety is an alkyl group, an alkyl substituted aryl group, an alkoxy substituted aryl group, and an aryl group substituted alkyl group or an aryl group.

In addition, the surfactant may comprise a tetraalkyldecine head group such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate and an oxyethylene tail group. May comprise any acetylene glycol surfactant. The surfactant may be an amphiphilic nonionic surfactant such as polyoxyethylene alkyl ether and polyoxyethylene alkanoic acid ester, the alkyl portion of which is saturated or partially unsaturated. Optionally, it is optionally branched C _6-30 alkyl. For example, amphiphilic nonionic surfactants are polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene monolaurate, polyoxyethylene monostearate , Polyoxyethylene distearate or polyoxyethylene monooleate. Similarly, the surfactant is a polyoxyethylene alkylphenyl ether or a polyoxyethylene alkyl cyclohexyl ether such as polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether or polyoxyethylene dinonyl phenyl ether. The alkyl group may be C _6-30 alkyl, may be saturated or partially unsaturated, and may optionally be branched.

The amphiphilic nonionic surfactant may also include a sorbitan alkanoic acid ether or a polyoxyethylene sorbitan alkanoic acid ester, the alkyl portion of which may be saturated or partially unsaturated. C _6-30 alkyl which may be optionally branched. For example, the amphiphilic nonionic surfactant is sorbitan monolaurate, sorbitan sesquioleate, sorbitan monopalmitate, sorbitan monostearate, sorbitan schioleate, sorbitan trioleate or sorbitan tristearate. And polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate or poly Oxyethylene sorbitan tetraoleate may be included.

  Alternatively, the surfactant is a polydimethicone moiety and a hydrophilic oxygen-containing moiety (eg, polyoxyethylene, polyoxyethylene and polyoxypropylene or polyoxyethylene and polyethylene or alkylpolyglucose, an ethoxylated ester or diester of alkylglucose). A polydimethicone block or graft copolymer comprising, consisting essentially of or consisting of The block or graft copolymer may comprise a polydimethicone moiety bonded to a combination of the above hydrophilic moieties, such as polyoxyethylene and polyoxypropylene copolymers.

  The surfactant is preferably hydrophilic so that it can be determined by the hydrophilic / lipophilic balance (HLB) value of the surfactant. The HLB value is an indicator of the solubility of the surfactant in water and is therefore related to the weight percent of the hydrophilic portion of the surfactant (eg, the weight percent of ethylene oxide). The surfactant HLB value, in some cases, in the case of a nonionic surfactant containing an ethylene oxide group, is equal to a value obtained by multiplying the mass percent (mass%) amount of the ethylene oxide group of the surfactant by 20. It can be approximated and shows values between 0-20. A low HLB value indicates a lipophilic surfactant (ie, having a small amount of hydrophilic groups), and a high HLB value indicates a hydrophilic surfactant (having a large amount of hydrophobic groups). Nonionic surfactants having an HLB of 10 or more have been classified as “hydrophilic” nonionic surfactants, and nonionic surfactants having an HLB of less than 10 are “lipophilic”. (Published by The HLB System, ICI United States, Inc., see 1976). In a preferred embodiment, the nonionic surfactant is a hydrophilic nonionic surfactant and thus has an HLB of at least 10 (eg, at least 12). In a preferred embodiment, the nonionic surfactant is a hydrophilic surfactant having an HLB of less than 19 (eg, less than 18).

  Preferred surfactants include polyoxyethylene nonylphenyl ether and polyoxyethylene dinonyl phenyl ether (eg, IGEPAL® surfactant from Rhone-Poulenc, ICANOL® from BASF) Surfactants and BASF's Lutensol® surfactants), polyoxyethylene-polyoxypropylene copolymers (eg, Pluronic® surfactants from BASF) and polydimethicone copolymers (compomer) ( For example, Silwet (registered trademark) surfactant manufactured by GE Silicones).

  Typically, the surfactant is present in the polishing composition at a concentration of at least 10 ppm, preferably at least 20 ppm (eg, at least 50 ppm, at least about 100 ppm, at least 150 ppm or at least 200 ppm). Typically, the surfactant is present at a concentration of at most 10,000 ppm, preferably at most 1000 ppm (eg, at most 750 ppm or at most 500 ppm).

(Inorganic insulating layer manufacturing method)
Examples of a method for manufacturing an inorganic insulating layer in which the polishing slurry for CMP of the present invention is used include a low pressure CVD method and a plasma CVD method. Formation of the silicon oxide insulating layer by the low pressure CVD method uses monosilane: SiH ₄ as a silicon (Si) source and oxygen: O ₂ as an 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 -based reactive 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 types of plasma generation methods: capacitive coupling type and inductive coupling type. The reaction _{gases, SiH 4, TEOS-O SiH} 4 -N 2 O -based gas and tetraethoxysilane using dinitrogen monoxide _(N 2 O) a (TEOS) was used in the Si source as an oxygen source as Si source ₂ type gas (TEOS-plasma CVD method) is mentioned. The substrate temperature is preferably in the range of 250 to 400 ° C., and the reaction pressure is preferably in the range of 67 to 400 Pa. Thus, the silicon oxide insulating layer of the present invention may be doped with elements such as phosphorus and boron.

Similarly, the formation of the silicon nitride layer by the low pressure CVD method uses dichlorosilane: SiH ₂ Cl ₂ as the Si source and ammonia: NH ₃ as the nitrogen source. It can be obtained by performing this SiH ₂ Cl ₂ —NH ₃ oxidation reaction 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 in the range of 300 to 400 ° C.

  As the substrate, there is a semiconductor substrate, that is, a semiconductor substrate at a stage where a circuit element and a wiring pattern are formed, a semiconductor substrate such as a semiconductor substrate at a stage where a circuit element is formed, and a substrate in which a silicon oxide insulating layer or a silicon nitride layer is formed. Can be used. By polishing the silicon oxide insulating layer or silicon nitride layer formed on such a semiconductor substrate with the above-mentioned polishing liquid for CMP, unevenness on the surface of the silicon oxide insulating layer is eliminated, and a smooth surface over the entire surface of the semiconductor substrate is obtained. can do. It can also be used for shallow trench isolation. In order to use for shallow trench isolation, the ratio of the rate of polishing the silicon oxide insulating layer to the rate of polishing the silicon nitride layer is “silicon oxide insulating layer polishing rate / silicon nitride layer polishing rate” of 10 or more. It is necessary to be. If the value of this ratio is too small, the difference between the polishing speed of the silicon oxide insulating layer and the polishing speed of the silicon nitride layer is reduced, and polishing can be stopped at a predetermined position when performing shallow trench isolation. Disappear. In addition, when the value of this ratio is 50 or more, the rate of polishing the silicon nitride layer is further reduced and polishing can be easily stopped, which is more preferable for shallow trench isolation.

(Polishing equipment)
As a polishing apparatus, a general polishing apparatus having a holder for holding a semiconductor substrate and a surface plate to which a polishing cloth (pad) is attached (a motor or the like whose rotation speed can be changed) is attached. 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 subjected to groove processing so that the polishing liquid for CMP 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 applied to the semiconductor substrate is 1 kg / cm ² or less so that no scratches are generated after polishing. Is preferred. In order to be used for shallow trench isolation, it is necessary that scratches are less likely to occur during polishing. During polishing, slurry is continuously supplied to the polishing cloth with a pump or the like. Although there is no restriction | limiting in this supply amount, it is preferable that the surface of polishing cloth is always covered with the slurry.

(Washing)
The semiconductor substrate after completion of polishing is preferably washed in running water and then dried after removing water droplets adhering to the semiconductor substrate using a spin dryer or the like. After forming the flattened shallow trench in this way, an aluminum wiring is formed on the silicon oxide insulating layer, and after forming the silicon oxide insulating layer again between the wirings and on the wiring by the above method, By polishing using a polishing liquid for CMP, irregularities on the surface of the insulating layer are eliminated, and the entire surface of the semiconductor substrate is smoothed. By repeating this process a predetermined number of times, a desired number of semiconductor layers are manufactured.

(Other)
The polishing liquid for CMP of the present invention includes not only a silicon oxide insulating layer formed on a semiconductor substrate, but also a silicon oxide insulating layer formed on a wiring board having a predetermined wiring, an inorganic insulating layer such as glass and silicon nitride, a photo Optical glass such as masks, lenses, and prisms, inorganic conductive films such as ITO, optical integrated circuits / optical switching elements / waveguides composed of glass and crystalline materials, optical fiber end faces, optical single crystals such as scintillators, solids Laser single crystals, blue laser LED sapphire substrates, semiconductor single crystals such as SiC, GaP, and GaAS, magnetic disk glass substrates, magnetic heads, and the like can be polished.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

(Preparation of abrasive particles)
<Abrasive particle 1>
(1) 10 L of 0.01 mol / L yttrium nitric acid aqueous solution was prepared, and urea was added to this aqueous solution so that the concentration of urea was 0.20 mol / L. After sufficiently stirring, the mixture was heated and stirred at 90 ° C. for 1 hour.
(2) A mixed solution of 0.08 mol / L yttrium nitric acid aqueous solution (300 mL) and 0.32 mol / L cerium nitric acid aqueous solution (300 mL) mixed in advance was added to the dispersion obtained in (1) at 10 mL / min. The addition was carried out at 90 ° C. while stirring with heating.
(3) To the dispersion obtained in (2) above, 50 mL of a 0.4 mol / L cerium nitric acid aqueous solution was added at 90 ° C. with heating and stirring at an addition rate of 10 mL / min.
(4) The abrasive precursor precipitated from the dispersion obtained in (3) was separated by a membrane filter, and fired at 600 ° C. to obtain abrasive particles 1.
(5) The obtained abrasive particles 1 were monodispersed particles having an average particle size of 0.40 μm and a particle size distribution coefficient of variation of 11%. Here, the average particle size was determined from a photograph of 100 abrasive particles taken with a scanning electron microscope (SEM), and the particle size distribution variation coefficient was determined by the following equation.
Coefficient of variation (%) = (standard deviation of particle size distribution / average particle size) × 100
(6) The abrasive particles were subjected to cross-section processing using a focused ion beam (FB-2000A) manufactured by Hitachi High-Technologies, and a surface passing through the vicinity of the particle center was cut out. From the cut surface, elemental analysis was performed using STEM-EDX (HD-2000) manufactured by Hitachi High-Technologies, and the particle composition distribution was evaluated. As a result, the abrasive particle 1 has a three-layer structure. In the cross section, a core layer (yttrium oxide) having a particle size of 0.3 μm, an intermediate layer (yttrium content: cerium content = 1: 4) having a thickness of 0.04 μm, and a cerium oxide shell layer formed on the outermost surface. I found out.

<Abrasive particle 2>
(1) 10 L of 0.05 mol / L yttrium nitric acid aqueous solution was prepared, and urea was added to this aqueous solution so that the concentration of urea was 1.0 mol / L. After sufficiently stirring, the mixture was heated and stirred at 90 ° C. for 1 hour.
(2) A mixed solution of 0.08 mol / L yttrium nitric acid aqueous solution (300 mL) and 0.32 mol / L cerium nitric acid aqueous solution (300 mL) mixed in advance was added to the dispersion obtained in (1) at 10 mL / min. The addition was carried out at 90 ° C. while stirring with heating.
(3) To the dispersion obtained in (2) above, 50 mL of a 0.4 mol / L cerium nitric acid aqueous solution was added at 90 ° C. with heating and stirring at an addition rate of 10 mL / min.
(4) The abrasive precursor precipitated from the dispersion obtained in (3) above was separated by a membrane filter and fired at 600 ° C. to obtain abrasive particles 2.
(5) As with the abrasive particles 1, the particle size and elemental analysis of the abrasive particles 2 were evaluated. Monodispersed particles having an average particle size of 0.62 μm and a coefficient of variation of 14%, a core layer (yttrium oxide) having a particle size of 0.57 μm, and an intermediate layer having a thickness of 0.02 μm (yttrium content: cerium content = 1) : 4) The shell layer had a three-layer structure of cerium oxide.

<Abrasive particle 3>
(1) 10 L of a 0.1 mol / L yttrium nitric acid aqueous solution was prepared, urea was added to this aqueous solution so that the concentration of urea was 2.0 mol / L, and after sufficient stirring, the mixture was heated and stirred at 90 ° C. for 1 hour.
(2) A mixed solution of 0.08 mol / L yttrium nitric acid aqueous solution (300 mL) and 0.32 mol / L cerium nitric acid aqueous solution (300 mL) mixed in advance was added to the dispersion obtained in (1) at 10 mL / min. The addition was carried out at 90 ° C. while stirring with heating.
(3) To the dispersion obtained in (2) above, 50 mL of a 0.4 mol / L cerium nitric acid aqueous solution was added at 90 ° C. with heating and stirring at an addition rate of 10 mL / min.
(4) The abrasive precursor precipitated from the dispersion obtained in (3) above was separated by a membrane filter and fired at 600 ° C. to obtain abrasive particles 3.
(5) The obtained abrasive particles 3 are monodisperse particles having an average particle diameter of 0.75 μm and a coefficient of variation of 19%, a core layer (yttrium oxide) having a particle diameter of 0.72 μm, and an intermediate thickness of 0.01 μm. The layer (yttrium content: cerium content = 1: 4) and the shell layer had a three-layer structure of cerium oxide.

<Abrasive particle 4>
(1) 10 L of 0.01 mol / L yttrium nitric acid aqueous solution was prepared, and urea was added to this aqueous solution so that the concentration of urea was 0.20 mol / L. After sufficiently stirring, the mixture was heated and stirred at 90 ° C. for 1 hour.
(2) To the dispersion obtained in (1), 300 mL of 0.4 mol / L yttrium nitric acid aqueous solution is added at a rate of (10-0.16 t) mL / min, and 0.4 mol / L cerium nitric acid aqueous solution is added. 300 mL was added with heating and stirring at 90 ° C. at an addition rate of (0.16 t) mL / min. However, t represents time (minutes).
(3) To the dispersion obtained in (2) above, 50 mL of a 0.4 mol / L cerium nitric acid aqueous solution was added at 90 ° C. with heating and stirring at an addition rate of 10 mL / min.
(4) The abrasive precursor precipitated from the dispersion obtained in (3) above was separated by a membrane filter and fired at 600 ° C. to obtain abrasive particles 4.
(5) The obtained abrasive particles 4 are monodisperse particles having an average particle size of 0.37 μm and a coefficient of variation of 15%, a core layer (yttrium oxide) having a particle size of 0.24 μm, and an intermediate thickness of 0.06 μm. 3 layers (intermediate layer with yttrium content: cerium content = 1: 1, cerium content increasing from core layer side to shell layer side with a constant concentration gradient), shell layer is 3 layers of cerium oxide It was a structure.

<Abrasive particle 5>
(1) Prepare 10 L of nitric acid aqueous solution containing 0.005 mol / L yttrium and 0.005 mol / L cerium, add urea so that the concentration is 0.20 mol / L, and stir well at 90 ° C. Stir for hours.
(2) A mixture of 600 mL of a 0.08 mol / L yttrium nitric acid aqueous solution and 600 mL of a 0.32 mol / L cerium nitric acid aqueous solution previously mixed with the dispersion obtained in (1) above was added at 10 mL / min. The addition was carried out at 90 ° C. while stirring with heating.
(3) To the dispersion obtained in (2) above, 50 mL of a 0.4 mol / L cerium nitric acid aqueous solution was added at 90 ° C. with heating and stirring at an addition rate of 10 mL / min.
(4) The abrasive precursor precipitated from the dispersion obtained in (3) was separated with a membrane filter and fired at 600 ° C. to obtain abrasive particles 5.
(5) The obtained abrasive particles 5 are monodisperse particles having an average particle size of 0.38 μm and a coefficient of variation of 19%. The abrasive particles 5 have a substantially two-layer structure composed of a 0.31 μm composite layer in which yttrium oxide and cerium oxide are mixed in the center and a shell layer made of cerium oxide having a layer thickness of 0.035 μm. It was. In the region having a diameter of 0.25 to 0.31 μm in the central composite layer, there was a region having a higher cerium ratio than the central portion from the composite layer to the shell layer.

<Abrasive particle 6>
(1) 10 L of 0.01 mol / L yttrium nitric acid aqueous solution was prepared, and urea was added to this aqueous solution so that the concentration of urea was 0.20 mol / L. After sufficiently stirring, the mixture was heated and stirred at 90 ° C. for 1 hour.
(2) To the dispersion obtained in (1) above, 600 mL of a 0.40 mol / L yttrium nitric acid aqueous solution previously mixed was added at 90 ° C. with heating and stirring at an addition rate of 10 mL / min.
(3) To the dispersion obtained in (2) above, 50 mL of a 0.4 mol / L cerium nitric acid aqueous solution was added at 90 ° C. with heating and stirring at an addition rate of 10 mL / min.
(4) The abrasive precursor precipitated from the dispersion obtained in (3) above was separated by a membrane filter and fired at 600 ° C. to obtain abrasive particles 6.
(5) The obtained abrasive particles 6 are monodisperse particles having an average particle size of 0.45 μm and a coefficient of variation of 15%, and are composed of a core layer (yttrium oxide) having a particle size of 0.43 μm and cerium oxide. It was a two-layer structure with a shell layer.

<Abrasive particle 7>
(1) 10 L of water was prepared, urea was added so that it might be 0.20 mol / L, and after stirring sufficiently, it was heated and stirred until it reached 90 ° C.
(2) A mixture of 600 mL of a 0.08 mol / L yttrium nitric acid aqueous solution and 600 mL of a 0.32 mol / L cerium nitric acid aqueous solution previously mixed with the dispersion obtained in (1) above was added at 10 mL / min. The addition was carried out at 90 ° C. while stirring with heating.
(3) The abrasive precursor precipitated from the dispersion obtained in (2) above was separated with a membrane filter and fired at 600 ° C. to obtain abrasive particles 7.
(4) The obtained abrasive particles 7 were monodisperse particles having an average particle diameter of 0.40 μm and a coefficient of variation of 13%, and had a single layer structure of yttrium content: cerium content = 1: 4.

<Abrasive particle 8>
By putting 2 kg of cerium carbonate hydrate in a platinum container and firing in air at 800 ° C. for 2 hours, about 1 kg of yellowish white powder was obtained. When this powder was phase-identified by X-ray diffraction, it was confirmed to be cerium oxide. 1 kg of this cerium oxide powder was dry-ground using a jet mill to obtain abrasive particles 8.
The obtained abrasive particles 8 are polydisperse particles (variation coefficient 88.2%) of cerium oxide 1 in which large polycrystalline particles in the range of 1 to 3 μm and polycrystalline particles in the range of 0.5 to 1 μm are mixed. It was a layer structure.

(Preparation of polishing liquid 1 for CMP)
10 g of the above abrasive particles 1, 20 g of 2-pyridinecarboxylic acid as an additive, polyoxyethylene nonylphenyl ether (“IGEPAL CO-890” manufactured by Rhonc-Polcnc) as the nonionic surfactant, the number of hydrophilic substances 1.5 g (average molecular weight 1760 [g / mol]) and 978.5 g of ionic water were mixed, and the pH was adjusted to 5 (liquid temperature 25 ° C.) with ammonium hydroxide while performing ultrasonic dispersion while stirring. The obtained slurry is filtered through a 0.8 micron filter, deionized water is further added, and the pH is adjusted to 5 (liquid temperature 25 ° C.) again, whereby polishing slurry 1 for CMP containing 0.1% by weight of abrasive particles. Got.

(Preparation of polishing liquid for CMP)
Polishing for CMP used for evaluation by preparing in the same manner as the polishing liquid for CMP 1 except that the composition and concentration of the abrasive particles and nonionic surfactant in the polishing liquid for CMP are changed to those shown in Table 1. A liquid was obtained. For comparison purposes, a polishing slurry for CMP containing no surfactant was also prepared.

(Evaluation of polishing rate)
A substrate on a surface plate on which a polishing pad (manufactured by Logitech Co., Ltd .; product name “PM5”) of a two-layer type semiconductor device polishing pad (manufactured by Nitta Haas; product name “IC1000 / SUBA400”) is attached. A silicon wafer with a diameter of 125 mm, on which a silicon oxide insulating layer produced by TEOS-plasma CVD method is formed, is set on a holder with a suction pad for mounting, with the insulating layer face down, so that the polishing load is 300 g / cm ^2. The weight was put on. While dropping on the surface plate at a rate of 50 mL / min for each CMP polishing liquid described in Table 1, the surface plate was rotated at 40 rpm for 2 minutes to polish the insulating layer.
After polishing, the wafer was removed from the holder, washed thoroughly with running water, and further washed with an ultrasonic cleaner for 20 minutes. After washing, water droplets were removed with a spin dryer and dried for 10 minutes with a 120 ° C. dryer. Using an optical interference type film thickness measuring device (manufactured by Chino Co., Ltd .: product name “IRM8599B”), the layer thickness change before and after polishing was measured, and the polishing rate was calculated.
The results are shown in Table 2.

Similarly, a silicon nitride layer produced by low-pressure CVD instead of a silicon oxide insulating layer produced by TEOS-plasma CVD was polished under the same conditions, the change in layer thickness before and after polishing was measured, and the polishing rate was calculated. . From the results of the layer thickness measurement, it was found that the silicon oxide insulating layer produced by the TEOS-plasma CVD method and the silicon nitride layer produced by the low pressure CVD method had a uniform thickness over the entire surface of the wafer.
The results are shown in Table 2.

From the polishing rate calculated as described above, the silicon oxide insulating layer polishing rate / silicon nitride layer polishing rate (the value of the ratio of the polishing rates) was calculated.
The results are shown in Table 2.

(Evaluation of polishing scratches)
In addition, the surface of the insulating layer was not scratched by visual observation under a mercury lamp light source, but was further observed in detail with a wafer appearance inspection device (manufactured by Olympus Corporation: product name “Olympus AL-2000”). .
The results are shown in Table 2.

(Dishing rating)
Similarly, a silicon oxide insulating layer in which convex portions of 20 μm square and a height of 5000 mm are formed at intervals of 100 μm is polished, and the amount of dent at the midpoint between the convex portions and the concave portions when the convex portions are polished is scanned by the scanning probe. It calculated | required with the microscope (Corporation | KK EPOLLYD service: Product name "SPI3800N / SPA-400"). Dishing was evaluated by this amount of dents.
The results are shown in Table 2.

(Evaluation of dispersion stability)
Each of the CMP polishing liquids was prepared and allowed to stand for 3 days, and the polishing rate, polishing scratches, and dishing were evaluated in the same manner as described above using this polishing liquid. Each CMP polishing liquid was used after being dispersed for 5 minutes by an ultrasonic disperser before polishing.
The results are shown in Table 2.

From the results shown in Table 2, it is recognized that Examples 1 to 15 obtain higher polishing rate and dispersion stability while suppressing generation of polishing flaws and dishing as compared with Comparative Examples 1 to 13. It was. Details are considered as follows.
In Examples 1 to 15, since the coefficient of variation of the abrasive particles is small, it is considered that a higher polishing rate could be realized while suppressing generation of polishing flaws and dishing. In addition, since Examples 1 to 15 do not include abrasive particles having a large particle diameter that promote aggregation, since the coefficient of variation of abrasive particles is small, aggregation is not promoted, and dispersion stability is improved. it is conceivable that.
On the other hand, since the abrasive particles of Comparative Examples 10 to 13 have a large coefficient of variation, it is considered that the abrasive particles having a large particle diameter are included more than in Examples 1 to 15. For this reason, it is considered that Comparative Examples 10 to 13 could not suppress the generation of polishing scratches and dishing. Furthermore, since Comparative Examples 10 to 13 contain abrasive particles having a large particle size that promote aggregation, aggregation and sedimentation are remarkably considered, and dispersion stability is considered to have decreased.
Moreover, since it is 500 g / mol or less of the hydrophilic substance of a nonionic surfactant about Comparative Examples 1-7, since it is a single particle composite particle of cerium and yttrium about Comparative Examples 8-9, There is a possibility that the cerium distribution is non-uniform, the adsorption of the dispersing agent or surfactant to the particle surface becomes non-uniform, the generation of polishing scratches and dishing cannot be suppressed, the aggregation is promoted, and the dispersion is stable It is considered that the sex has declined.

1 Core layer 2 Intermediate layer 3 Shell layer A Abrasive particles

Claims (2)

Non-ion having an abrasive, an additive having a functional group having _a pKa in the range of 4 to 9, a hydrophilic part and a lipophilic part, wherein the hydrophilic part has a number average molecular weight of 500 g / mol or more A polishing slurry for CMP having a pH of 7 or less, comprising a surfactant and water,
The abrasive particles used for the abrasive have a core-shell structure consisting of a core layer and a shell layer,
The core layer is made of aluminum (Al), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), Copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium (Zr), indium (In), tin (Sn), yttrium (Y), gadolinium (Gd), terbium (Tb), From dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), tungsten (W), bismuth (Bi), thorium (Th) and alkaline earth metals Contains an oxide of at least one element selected, and
The CMP polishing liquid, wherein the shell layer contains cerium oxide. The abrasive particles further have an intermediate layer between the core layer and the shell layer; and
The intermediate layer is made of aluminum (Al), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), Copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium (Zr), indium (In), tin (Sn), yttrium (Y), gadolinium (Gd), terbium (Tb), From dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), tungsten (W), bismuth (Bi), thorium (Th) and alkaline earth metals The oxide for CMP according to claim 1, comprising an oxide of at least one element selected and cerium oxide. Migakueki.

Images