JP6482200B2 - Polishing composition - Google Patents

Description

  The present invention relates to a polishing composition. Specifically, the present invention relates to a polishing composition that is preferably used mainly for polishing semiconductor substrates such as silicon wafers and other polishing objects.

  Precision polishing using a polishing liquid is performed on the surface of materials such as metals, metalloids, nonmetals, and oxides thereof. For example, the surface of a silicon wafer used as a component of a semiconductor product is generally finished to a high-quality mirror surface through a lapping process (rough polishing process) and a polishing process (precision polishing process). The polishing process typically includes a preliminary polishing process (preliminary polishing process) and a final polishing process (final polishing process). Patent documents 1-4 are mentioned as technical literature about a constituent for polish mainly used for a use which polishes semiconductor substrates, such as a silicon wafer. Patent documents 5 to 9 are technical documents disclosing silica abrasive grains having a plurality of protrusions on the surface.

JP 07-221059 A JP 2000-239653 A JP 2001-77063 A JP 2005-268667 A JP2013-98392A JP2013-115151A JP2012-104800A JP 2013-80752 A JP 2013-121631 A

  In recent years, higher quality surfaces have been required for semiconductor substrates such as silicon wafers and other substrates. In particular, in consideration of productivity and cost, it is desired to obtain a higher quality surface without extending the total polishing time (total polishing time) required for the polishing process. As one of the techniques, the polishing process is performed while maintaining the surface quality that can be reached by the polishing process with respect to any polishing process upstream of the final polishing process among the polishing processes included in the polishing process. It would be beneficial if the polishing rate could be improved. This is because the time that can be spent in the downstream polishing process (for example, final polishing process) is increased, and the polishing object can be polished to a smoother surface. However, in general, the surface quality after polishing and the polishing rate are in a contradictory relationship, and the surface quality tends to decrease when the polishing rate is improved.

  This invention is made | formed in view of said situation, and it aims at providing the polishing composition which can improve a polishing rate, implement | achieving favorable surface quality.

According to the present invention, a polishing composition comprising silica particles as abrasive grains and a basic compound as a polishing accelerator is provided. The ratio (A / B) of the total surface area A [m ² / kg composition] of the abrasive grains to the total volume B [m ³ / kg composition] of abrasive grains contained in 1 kg of the polishing composition is 7 0.0 × 10 ⁷ or more.
A large ratio (A / B) means that the surface area per abrasive grain (silica particle) contained in the composition is large. In this way, by using abrasive grains having a predetermined surface area or more, in the polishing composition, the basic compound as the polishing accelerator is favorably adsorbed on the surface of the silica particles and efficiently reaches the object to be polished. . As a result, the chemical action by the polishing accelerator is sufficiently exhibited, and the polishing rate can be improved while realizing good surface quality.

In a preferred aspect of the technology disclosed herein, the ratio (A / B) is 9.0 × 10 ⁷ or more. With this configuration, the polishing rate is further improved.

In a preferred aspect of the technology disclosed herein, the total surface area A [m ² / kg composition] of the abrasive grains is 400 or more. That the total surface area A is a predetermined value or more means that the product of the surface area and the concentration of the abrasive grains is a predetermined level or more in the polishing composition. By setting the total surface area A to a predetermined value or more, the total amount of the polishing accelerator adsorbed on the silica particles is increased, and the polishing rate improving action by the polishing accelerator is better exhibited.

（式中、Ｘ^１は、水素原子、アミノ基、またはＣ^１原子への結合を表す。Ｘ^１がＣ^１原子への結合を表す場合、Ｈ^１原子は存在しない。Ｘ^２は、水素原子、アミノ基、アミノアルキル基、またはＣ^１原子への結合を表す。Ｘ^２がＣ^１原子への結合を表す場合、Ｃ^１−Ｎ^１結合は二重結合となり、Ｈ^２原子は存在しない。ｌは１〜６の整数、ｍは１〜４の整数、ｎは０〜４の整数である。）；で表される化合物を含む。砥粒および研磨促進剤を用いるケミカルメカニカルポリシング（ＣＭＰ）法において、研磨促進剤としてテトラメチルアンモニウムヒドロキシド（ＴＭＡＨ）がよく利用されているが、環境負荷軽減等の観点からＴＭＡＨの使用を避けたいという要請がある。上記化合物は、ＴＭＡＨに代わる研磨促進剤として良好に機能し得る。 In a preferred embodiment of the technology disclosed herein, the basic compound is
The following general formula (A):

(Wherein, ^{X 1} is a hydrogen atom, an amino group or if .X ¹ representing the bond to the ^{C 1} atom represents a bond to ^{C 1} atom, .X ^{2 where H 1} atom is not present, is a hydrogen atom Represents an amino group, an aminoalkyl group, or a bond to the C ¹ atom, and when X ² represents a bond to the C ¹ atom, the C ¹ -N ¹ bond is a double bond and there is no H ² atom. 1 is an integer of 1 to 6, m is an integer of 1 to 4, and n is an integer of 0 to 4). Tetramethylammonium hydroxide (TMAH) is often used as a polishing accelerator in a chemical mechanical polishing (CMP) method using abrasive grains and a polishing accelerator, but it is desirable to avoid the use of TMAH from the viewpoint of reducing environmental impact. There is a request. The above compound can function well as a polishing accelerator in place of TMAH.

  In a preferred embodiment, the polishing composition is typically alkaline, and specifically the pH of the polishing composition is 8-12. By this, the polishing rate improvement effect can be exhibited more effectively.

  In a preferred embodiment of the technology disclosed herein, the polishing composition is substantially free of an oxidizing agent. When an oxidizing agent is contained in the polishing composition, the surface of the polishing object is oxidized and an oxide film is formed by supplying the composition to the polishing object, and thereby the polishing rate tends to decrease. Can be. By using a polishing composition that substantially does not contain an oxidant, a reduction in the polishing rate as described above can be avoided.

  In a preferred embodiment of the technology disclosed herein, the silica particles are colloidal silica. According to the technique disclosed herein, in polishing using colloidal silica as abrasive grains, both surface quality and polishing rate can be preferably achieved.

  In a preferred embodiment of the technology disclosed herein, the polishing composition is used for polishing a silicon wafer. The polishing composition disclosed herein is preferably used for polishing a silicon wafer that has undergone lapping, for example. Among these, it is particularly preferably used for preliminary polishing of a silicon wafer.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

<Abrasive>
The polishing composition disclosed herein contains abrasive grains. The ratio (A / B) of the total surface area A [m ² / kg composition] of the abrasive grains to the total volume B [m ³ / kg composition] of abrasive grains contained in 1 kg of the polishing composition is 7.0 × 10 ⁷ or more. This point will be described. In the CMP method using abrasive grains and a polishing accelerator, the abrasive grains contribute mainly to the polishing of the object to be polished by mechanical action, and the polishing accelerators mainly contribute to the polishing of the object to be polished by chemical action. Rather than exhibiting the polishing ability independently of each other, it is considered that efficient mechanical polishing and chemical action are related to each other to achieve efficient polishing. In such a CMP method, the present inventors paid attention to the position (relative arrangement relationship) of the polishing accelerator with respect to the abrasive grains in the polishing liquid. Specifically, the basic compound used as a polishing accelerator can exhibit adsorptivity to the surface of silica particles as abrasive grains in the polishing liquid. Accordingly, it is considered that the polishing accelerator adsorbed or close to the surface of the abrasive grains reaches the surface of the object to be polished more efficiently because of the abrasive grains. As a result of various investigations on the abrasive grains based on this knowledge, the chemical action of the polishing accelerator is suitably exhibited by setting the abrasive grain surface area capable of adsorbing the polishing accelerator in the polishing composition to a predetermined value or more. It became clear that That is, by using a polishing composition having the ratio (A / B) of a predetermined value or more, the chemical action by the polishing accelerator is sufficiently exerted, and the polishing rate is improved while realizing good surface quality. Can do.

The ratio (A / B) preferably shows a larger value from the viewpoint of improving the polishing rate. Specifically, the ratio (A / B) is preferably 9.0 × 10 ⁷ or more, more preferably 1.2 × 10 ⁸ or more, and further preferably 1.5 × 10 ⁸ or more. Yes, particularly preferably 1.8 × 10 ⁸ or more. The upper limit of the ratio (A / B) is not particularly limited, but if the surface area of the abrasive grains is too large, the surface quality may deteriorate. In consideration of this, the upper limit of the ratio (A / B) is usually preferably 1.0 × 10 ⁹ or less, more preferably 5.0 × 10 ⁸ or less, and 4.0. More preferably, it is set to 10 ⁸ or less.

The total surface area A [m ² / kg composition] of the abrasive grains contained in 1 kg of the polishing composition is expressed by the formula:
A = abrasive grain concentration [wt%] × 10 × abrasive grain specific surface area [m ² / g];
It is requested from. The specific surface area of the abrasive grains is measured by the BET method. The specific surface area can be measured using, for example, a surface area measuring device manufactured by Micromeritex Corporation, a trade name “Flow Sorb II 2300”.
In addition, the total volume B [m ³ / kg composition] of abrasive grains contained in 1 kg of the polishing composition is expressed by the formula:
B = abrasive grain concentration [wt%] × 10 / abrasive grain density [g / cm ³ ] × 10 ⁻⁶
; The same applies to the embodiments described later.

From the viewpoint of improving the polishing rate, the total surface area A [m ² / kg composition] of the abrasive grains is preferably 400 or more. By setting the total surface area A to a predetermined value or more, the total amount of the polishing accelerator adsorbed on the silica particles as the abrasive grains is increased, and the polishing rate improving action by the polishing accelerator is better exhibited. The total surface area A is more preferably 450 or more, and even more preferably 500 or more. The upper limit of the total surface area A is not particularly limited, but if the total surface area A is too large, the surface quality may be deteriorated. Therefore, it is usually preferably 3000 or less, more preferably 2000 or less, and 1000 More preferably (for example, 600 or less).

  Silica particles are used as the abrasive grains. For example, when the technique disclosed herein is applied to a polishing composition that can be used for polishing a silicon wafer, it is particularly preferable to use silica particles as abrasive grains. The reason is as follows. That is, when the object to be polished is a silicon wafer, if silica particles composed of the same elements and oxygen atoms as the object to be polished are used as abrasive grains, no metal or metalloid residue different from silicon is generated after polishing. Therefore, there is no possibility of contamination of the silicon wafer surface or deterioration of electrical characteristics as a silicon wafer due to diffusion of a metal or semi-metal different from silicon into the object to be polished. Furthermore, since the hardness of silicon and silica is close, polishing can be performed without undue damage to the silicon wafer surface. A polishing composition containing only silica particles as abrasive grains is exemplified as a preferred polishing composition from such a viewpoint. Silica has a property that it can be easily obtained in high purity. This is also cited as the reason why silica particles are preferable as the abrasive grains. Specific examples of the silica particles include colloidal silica, fumed silica, precipitated silica and the like. Colloidal silica and fumed silica are preferable as silica particles from the viewpoint that scratches are hardly generated on the surface of the object to be polished and a surface having a lower haze can be realized. Of these, colloidal silica is preferred. For example, colloidal silica can be preferably employed as abrasive grains of a polishing composition used for polishing a silicon wafer (at least one of preliminary polishing and final polishing, preferably preliminary polishing).

  The shape of the silica particles disclosed herein is not particularly limited, and may be spherical or non-spherical. Specific examples of the non-spherical silica particles include silica particles having a peanut shape (that is, a shape of a peanut shell), a cocoon shape, a shape with a protrusion, and the like. As the silica particles, one type having the same shape may be used alone, or two or more types having different shapes may be used in combination. Especially, the silica particle which has a peanut shape, a bowl shape, and a shape with a protrusion is preferable, and a silica particle with a protrusion is more preferable. Spherical silica particles, peanut-shaped silica particles, and cocoon-shaped silica particles are typical examples included in the concept of silica particles having a shape that does not have a plurality of protrusions on the surface.

  The silica particles with protrusions are typically silica particles having a plurality of protrusions on the surface. Such a silica particle with a projection is excellent in the adsorptivity of the polishing accelerator because the surface area of one particle is large. From the viewpoint of increasing the surface area per particle, the number of protrusions in the silica particles with protrusions is preferably 3 or more and more preferably 5 or more on an average per particle. Here, the protrusions have a height and width that are sufficiently smaller than the particle diameter of the silica particles. In addition, about the silica particle with a protrusion in the technique disclosed here, the width | variety of a protrusion means the width | variety in the base part of a protrusion. Further, the height of the protrusion refers to the distance between the base of the protrusion and the portion of the protrusion farthest from the base. The height of each protrusion of the silica particles with protrusions and the width at the base thereof can be obtained by analyzing a scanning electron microscope image of the silica particles with protrusions using general image analysis software.

  In the technique disclosed here, the average protrusion degree of the silica particles with protrusions is not particularly limited. From the viewpoint of increasing the surface area per particle, silica particles with protrusions having an average protrusion degree of 0.170 or more (for example, 0.190 or more, typically 0.210 or more, and further 0.230 or more) should be used. Can do. The average protrusion degree is preferably 0.245 or more, and more preferably 0.255 or more. When the average protrusion degree of the silica abrasive grains with protrusions increases, the shape of the protrusions tends to be sharp. As a result, the effect of improving the polishing rate can be better exhibited. The upper limit of the average protrusion degree is not particularly limited. From the viewpoint of ease of production and strength, the average degree of protrusion of the silica particles with protrusions is usually suitably 0.5 or less, and preferably 0.4 or less. In this specification, the average protrusion degree refers to the height of the protrusions on the surface of the abrasive grains having a particle diameter larger than the volume average particle diameter of the abrasive grains, and the base of the protrusions. When the width at is W, it means the average value of the values (projection degree) represented by H / W.

  The average height of the protrusions in the silica particles with protrusions having a particle diameter larger than the volume average particle diameter among the silica particles with protrusions is approximately 1.0 nm or more (for example, 2.0 nm or more, typically 3.0 nm or more). Appropriately, it is preferably 3.5 nm or more, more preferably 4.0 nm or more. As the average height of the protrusions increases, the effect of improving the polishing rate tends to increase. The upper limit of the average height of the protrusion is not particularly limited. From the viewpoint of manufacturability and strength, the average height of the protrusions is usually suitably 10 nm or less, and preferably 7.0 nm or less.

  The density of the silica constituting the silica particles is preferably 1.5 or more, more preferably 1.6 or more, and even more preferably 1.7 or more. By increasing the density of silica, the polishing rate can be improved when polishing an object to be polished (for example, a silicon wafer). From the viewpoint of reducing scratches generated on the surface of the object to be polished (surface to be polished), silica particles having a density of 2.3 or less are preferable. As the density of the abrasive grains (typically silica), a value measured by a liquid replacement method using ethanol as a replacement liquid may be employed.

  The polishing composition disclosed herein may contain abrasive grains other than silica particles as long as the effects of the present invention are not significantly impaired. The abrasive grains other than the silica particles (hereinafter also referred to as “arbitrary abrasive grains”) may be inorganic particles other than silica, organic particles, or organic-inorganic composite particles. Specific examples of the inorganic particles include alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, bengara particles, etc .; silicon nitride particles And nitride particles such as boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; carbonates such as calcium carbonate and barium carbonate; Specific examples of the organic particles include polymethyl methacrylate (PMMA) particles and poly (meth) acrylic acid particles (here, (meth) acrylic acid is a generic term for acrylic acid and methacrylic acid). And polyacrylonitrile particles. Arbitrary abrasive can be used individually by 1 type or in combination of 2 or more types.

  The content of the optional abrasive grains is suitably, for example, 30% by weight or less, preferably 20% by weight or less, and preferably 10% by weight or less, based on the total weight of the abrasive grains contained in the polishing composition. More preferably. The technique disclosed herein can be preferably implemented in an embodiment in which the content of the optional abrasive grains is 5% by weight or less of the total weight of the abrasive grains contained in the polishing composition. The polishing composition may be substantially free of any abrasive grains. Here, the phrase “the polishing composition does not substantially contain any abrasive grains” means that the optional abrasive grains are not blended at least intentionally.

  In the technology disclosed herein, the abrasive grains contained in the polishing composition may be in the form of primary particles or in the form of secondary particles in which a plurality of primary particles are associated. Further, abrasive grains in the form of primary particles and abrasive grains in the form of secondary particles may be mixed. In a preferred embodiment, at least a part of the abrasive grains is contained in the polishing composition in the form of secondary particles.

The average primary particle diameter of the abrasive grains is not particularly limited, but is preferably 5 nm or more, more preferably 10 nm or more, and particularly preferably 20 nm or more from the viewpoint of polishing rate and the like. From the viewpoint of obtaining a higher polishing effect, the average primary particle size is preferably 25 nm or more, and more preferably 30 nm or more. Abrasive grains having an average primary particle diameter of 40 nm or more may be used. Further, from the viewpoint of storage stability (for example, dispersion stability), the average primary particle diameter of the abrasive grains is preferably 100 nm or less, more preferably 80 nm or less, still more preferably 70 nm or less, for example 60 nm or less. In the technology disclosed herein, the average primary particle diameter of the abrasive grains is calculated by, for example, the formula D = 2727 / S (nm) from the specific surface area (m ² / g) measured by the BET method. be able to. The specific surface area can be measured using, for example, a surface area measuring device manufactured by Micromeritex Corporation, a trade name “Flow Sorb II 2300”.

  The average secondary particle diameter (secondary particle diameter) of the abrasive grains is not particularly limited, but is preferably 10 nm or more, more preferably 15 nm or more, and further preferably 20 nm or more from the viewpoint of polishing rate and the like. From the viewpoint of obtaining a higher polishing effect, the average secondary particle diameter is particularly preferably 40 nm or more (for example, 50 nm or more, typically 60 nm or more). Further, from the viewpoint of storage stability (for example, dispersion stability), the average secondary particle diameter of the abrasive grains is suitably 200 nm or less, preferably 150 nm or less, more preferably 100 nm or less (for example, 80 nm or less). . The average secondary particle diameter of the abrasive grains can be measured, for example, by a dynamic light scattering method using a model “UPA-UT151” manufactured by Nikkiso Co., Ltd. The same applies to the embodiments described later.

  Although not particularly limited, the average value (average aspect ratio) of the major axis / minor axis ratio of the abrasive grains is preferably 1.01 or more, more preferably 1.05 or more (eg, 1.1 or more). Higher polishing rates can be achieved by increasing the average aspect ratio of the abrasive grains. The average aspect ratio of the abrasive grains is preferably 3.0 or less, more preferably 2.0 or less, and still more preferably 1.5 or less, from the viewpoints of polishing rate and scratch reduction. According to the technology disclosed herein, even in an embodiment using abrasive grains having an average aspect ratio of less than 1.25 (for example, 1.20 or less, typically less than 1.15), polishing is performed while achieving good surface quality. The rate can be improved.

  The shape (outer shape) and average aspect ratio of the abrasive grains can be grasped by, for example, observation with an electron microscope. As a specific procedure for grasping the average aspect ratio, for example, a predetermined number (for example, 200) of abrasive particles capable of recognizing the shape of independent particles using a scanning electron microscope (SEM) is used. Draw the smallest rectangle that circumscribes the image. For the rectangle drawn for each particle image, the value obtained by dividing the length of the long side (major axis value) by the length of the short side (minor axis value) is the major axis / minor axis ratio (aspect ratio). ). An average aspect ratio can be obtained by arithmetically averaging the aspect ratios of the predetermined number of particles. The same applies to the embodiments described later.

The specific surface area of the abrasive grains disclosed herein is not particularly limited as long as the ratio (A / B) is within a predetermined range. Usually, it is appropriate to use abrasive grains having a specific surface area of 20 to 600 m ² / g. The specific surface area of the abrasive is preferably 25 m ² / g or more, more preferably 30 m ² / g or more, and further preferably 35 m ² / g or more (for example, 40 m ² / g) from the viewpoint of improving the polishing rate. Above). From the standpoint of maintaining good surface quality, the specific surface area is preferably 300 m ² / g or less, more preferably 200 m ² / g or less, and even more preferably 150 m ² / g or less. It is preferably 120 m ² / g or less (for example, 100 m ² / g or less, typically 70 m ² / g or less). What is necessary is just to measure the specific surface area of an abrasive grain by the above-mentioned method. The same applies to the embodiments described later.

<Polishing accelerator>
The polishing composition disclosed herein contains a basic compound as a polishing accelerator. The polishing accelerator is a component that functions to chemically polish an object to be polished and contributes to an improvement in the polishing rate. By using a basic compound as a polishing accelerator, the pH of the polishing composition is increased, and the dispersion state of the abrasive grains and the water-soluble polymer is improved. Thereby, the dispersion stability of the polishing composition is improved, and the mechanical polishing action by the abrasive grains is improved. The basic compound may be an organic basic compound such as cyclic amines or an inorganic basic compound. A basic compound can be used individually by 1 type or in combination of 2 or more types from what is illustrated below.

  In a preferred embodiment, the polishing composition contains a compound (A) represented by the following general formula (A) as a basic compound. By using the compound (A) as a polishing accelerator, the polishing rate tends to be greatly improved.

ここで、一般式（Ａ）中のＸ^１は、水素原子、アミノ基、またはＣ^１原子への結合を表す。Ｘ^１がＣ^１原子への結合を表す場合、Ｈ^１原子は存在しない。上記Ｘ^１は、好ましくはアミノ基またはＣ^１原子への結合であり、より好ましくはアミノ基である。Ｘ^２は、水素原子、アミノ基、アミノアルキル基、またはＣ^１原子への結合を表す。Ｘ^２がＣ^１原子への結合を表す場合、Ｃ^１−Ｎ^１結合は二重結合となり、Ｈ^２原子は存在しない。上記Ｘ^２は、好ましくは水素原子または炭素原子数１〜４（典型的には２または３）のアミノアルキル基であり、より好ましくは水素原子である。ｌは０〜６（好ましくは１〜６、より好ましくは２，３または４）の整数、ｍは１〜４（好ましくは２または３）の整数、ｎは０〜４（好ましくは０または１）の整数である。

Here, X ¹ in the general formula (A) represents a hydrogen atom, an amino group, or a bond to a C ¹ atom. When X ¹ represents a bond to a C ¹ atom, there is no H ¹ atom. X ¹ is preferably an amino group or a bond to a C ¹ atom, and more preferably an amino group. X ² represents a hydrogen atom, an amino group, an aminoalkyl group, or a bond to a C ¹ atom. When X ² represents a bond to the C ¹ atom, the C ¹ -N ¹ bond is a double bond and there is no H ² atom. X ² is preferably a hydrogen atom or an aminoalkyl group having 1 to 4 carbon atoms (typically 2 or 3), more preferably a hydrogen atom. l is an integer of 0-6 (preferably 1-6, more preferably 2, 3 or 4), m is an integer of 1-4 (preferably 2 or 3), and n is 0-4 (preferably 0 or 1). ).

Examples of the compound (A) include cyclic amine compounds in which both X ¹ and X ² in the general formula (A) are hydrogen atoms. In this case, l in the general formula (A) may be 0 or 1-6. m is 1-4, Preferably it is 2-4. n is 0-4, preferably 1-4. Specific examples of such cyclic amines include piperazine, N-methylpiperazine, N-ethylpiperazine, N-butylpiperazine; and the like. Further preferred examples, X ² in formula (A) is a hydrogen atom and X ¹ is a cyclic amine is an amino group. In this case, l in the general formula (A) is 0 to 6, preferably 2 to 6. m is 1-4, Preferably it is 2-4. n is 0-4, preferably 1-4. Specific examples of such cyclic amines include N-aminomethylpiperazine, N-aminoethylpiperazine, N-aminopropylpiperazine; and the like. In addition, a cyclic amine in which X ¹ in the general formula (A) is an amino group and X ² is an aminoalkyl group is also preferably used. Specific examples of such cyclic amines include 1,4- (bisaminoethyl) piperazine, 1,4- (bisaminopropyl) piperazine; and the like.

Other suitable examples of the compound (A) include cyclic diamine compounds in which both X ¹ and X ^{2 in} the general formula (A) represent a bond to a C ¹ atom. In this case, l in the general formula (A) is 0 to 6, preferably 3 to 6. m is 1 to 4, preferably 2 or 3. n is 0-4, preferably 0-2. Specific examples of such cyclic diamine compounds include 1,8-diazabicyclo [5.4.0] undec-7-ene, 1,5-diazabicyclo [4.3.0] -5-nonene. .

Other examples of organic basic compounds include quaternary ammonium salts such as tetraalkylammonium salts. The anion in the ammonium salt may be, for example, OH ⁻ , F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , BH ₄ ⁻ or the like. For example, quaternary ammonium salts such as choline, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide can be used.
Other examples of organic basic compounds include quaternary phosphonium salts such as tetraalkylphosphonium salts. The anion in the phosphonium salt may be, for example, OH ⁻ , F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , BH ₄ ⁻ or the like. For example, halides and hydroxides such as tetramethylphosphonium, tetraethylphosphonium, tetrapropylphosphonium, and tetrabutylphosphonium can be used.
Other examples of organic basic compounds include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N- (β-aminoethyl) ethanolamine, hexamethylenediamine, diethylenetriamine, triethylene. Amines such as tetramine; 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, 2- (methylamino) pyridine, 3- (methylamino) pyridine, 4- (methylamino) pyridine, 2- (dimethylamino) ) Aminopyridines such as pyridine, 3- (dimethylamino) pyridine, 4- (dimethylamino) pyridine; azoles such as imidazole and triazole; guanidine; dia such as 1,4-diazabicyclo [2.2.2] octane Bicyclo alkanes; and the like.

  Examples of inorganic basic compounds include ammonia; ammonia, alkali metal or alkaline earth metal hydroxides, carbonates, bicarbonates, and the like. Specific examples of the hydroxide include potassium hydroxide and sodium hydroxide. Specific examples of the carbonate or bicarbonate include ammonium bicarbonate, ammonium carbonate, potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate and the like.

  When an inorganic basic compound is used, the amount used is usually less than 1 mol per kg of abrasive grains, preferably less than 0.5 mol from the viewpoint of surface quality and the like. More preferably, it is less than 2 moles. Alternatively, the polishing composition disclosed herein may be a composition that does not substantially contain an inorganic basic compound.

  The amount of the polishing accelerator contained in the polishing composition can be, for example, 0.0001 mol or more per 1 kg of the polishing composition. From the viewpoint of improving the polishing rate, the content of the polishing accelerator is preferably 0.001 mol or more (eg, 0.005 mol or more, typically 0.01 mol or more) per 1 kg of the polishing composition. Since the surface quality may be impaired when the amount of the polishing accelerator is too large, it is usually appropriate to set the amount of the polishing accelerator per 1 kg of abrasive grains to 3 mol or less, and 1 mol or less. For example, it may be less than 0.4 mol (typically less than 0.1 mol).

<Water>
As the water constituting the polishing composition disclosed herein, ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, or the like can be preferably used. The water to be used preferably has, for example, a total content of transition metal ions of 100 ppb or less in order to avoid as much as possible the action of other components contained in the polishing composition. For example, the purity of water can be increased by operations such as removal of impurity ions with an ion exchange resin, removal of foreign matter with a filter, distillation, and the like.
The polishing composition disclosed herein may further contain an organic solvent (lower alcohol, lower ketone, etc.) that can be uniformly mixed with water, if necessary. Usually, it is preferable that 90 volume% or more of the solvent contained in polishing composition is water, and it is more preferable that 95 volume% or more (typically 99-100 volume%) is water.

<Chelating agent>
The polishing composition disclosed herein can contain a chelating agent as an optional component. The chelating agent functions to suppress contamination of the object to be polished by metal impurities by forming complex ions with metal impurities that can be contained in the polishing composition and capturing them. A chelating agent can be used individually by 1 type or in combination of 2 or more types.
Examples of chelating agents include aminocarboxylic acid chelating agents and organic phosphonic acid chelating agents. Examples of aminocarboxylic acid chelating agents include ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid sodium, nitrilotriacetic acid, nitrilotriacetic acid sodium, nitrilotriacetic acid ammonium, hydroxyethylethylenediaminetriacetic acid, hydroxyethylethylenediamine sodium triacetate, diethylenetriaminepentaacetic acid Diethylenetriamine sodium pentaacetate, triethylenetetramine hexaacetic acid and sodium triethylenetetramine hexaacetate. Examples of organic phosphonic acid chelating agents include 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetrakis (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic). Acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid Ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid and α-methylphospho Nosuccinic acid is included. Of these, organic phosphonic acid-based chelating agents are more preferable, and aminotri (methylenephosphonic acid), ethylenediaminetetrakis (methylenephosphonic acid), and diethylenetriaminepenta (methylenephosphonic acid) are particularly preferable.

Although not particularly limited, the content of the chelating agent can be 0.000005 mol or more per liter (L) of the polishing composition. From the viewpoint of suppression of contamination by metal impurities, the content of the chelating agent is preferably 0.00001 mol / L or more, more preferably 0.00003 mol / L or more, and 0.00005 mol / L or more. More preferably. The upper limit of the content of the chelating agent per liter of the polishing composition is not particularly limited, but it is usually appropriate that the content of the chelating agent per liter of the polishing composition is 0.005 mol / L or less. , 0.002 mol / L or less is preferable, and 0.001 mol / L or less is more preferable.
The content of the chelating agent can be, for example, 0.01 parts by weight or more with respect to 100 parts by weight of the abrasive grains, preferably 0.05 parts by weight or more, and 0.1 parts by weight or more. More preferably, it is more preferably 0.2 parts by weight or more. The content of the chelating agent with respect to 100 parts by weight of the abrasive is suitably 5 parts by weight or less, preferably 3 parts by weight or less, and more preferably 1 part by weight or less.

<Other ingredients>
The polishing composition disclosed herein is a water-soluble polymer, surfactant, organic acid, organic acid salt, inorganic acid, inorganic acid salt, preservative, anticorrosive, as long as the effects of the present invention are not significantly impaired. You may further contain the well-known additive which can be used for polishing compositions (typically polishing composition used for the polishing process of a silicon wafer), such as a mold agent, as needed.

  Examples of the water-soluble polymer include cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polymers containing nitrogen atoms, vinyl alcohol polymers, and the like. Specific examples include hydroxyethyl cellulose, pullulan, random copolymer or block copolymer of ethylene oxide and propylene oxide, polyvinyl alcohol, polyisoprene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyisoamylene sulfonic acid. Polystyrene sulfonate, polyacrylate, polyvinyl acetate, polyethylene glycol, polyvinyl pyrrolidone, polyacryloylmorpholine, polyacrylamide and the like. A water-soluble polymer can be used singly or in combination of two or more. The polishing composition disclosed herein can also be preferably implemented in an embodiment that does not substantially contain a water-soluble polymer.

The polishing composition disclosed herein may contain a surfactant (typically a water-soluble organic compound having a molecular weight of less than 1 × 10 ⁴ ) as an optional component. By using the surfactant, the dispersion stability of the polishing composition can be improved. Surfactant can be used individually by 1 type or in combination of 2 or more types.
As the surfactant, an anionic or nonionic surfactant can be preferably used. From the viewpoint of low foaming property and ease of pH adjustment, a nonionic surfactant is more preferable. For example, oxyalkylene polymers such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol; polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene fatty acid ester, polyoxyethylene glyceryl ether fatty acid Nonionic surfactants such as esters, polyoxyalkylene adducts such as polyoxyethylene sorbitan fatty acid esters; copolymers of plural types of oxyalkylene (diblock type, triblock type, random type, alternating type); It is done.
The amount of the surfactant used is suitably 5 g or less per kg of abrasive grains, preferably 2 g or less, and more preferably 1 g or less. The polishing composition disclosed herein can also be preferably implemented in an embodiment that does not substantially contain a surfactant.

Examples of organic acids include fatty acids such as formic acid, acetic acid and propionic acid, aromatic carboxylic acids such as benzoic acid and phthalic acid, citric acid, oxalic acid, tartaric acid, malic acid, maleic acid, fumaric acid, succinic acid, organic Examples include sulfonic acid and organic phosphonic acid. Examples of organic acid salts include alkali metal salts (sodium salts, potassium salts, etc.) and ammonium salts of organic acids. Examples of inorganic acids include sulfuric acid, nitric acid, hydrochloric acid, carbonic acid and the like. Examples of inorganic acid salts include alkali metal salts (sodium salts, potassium salts, etc.) and ammonium salts of inorganic acids. An organic acid and its salt, and an inorganic acid and its salt can be used individually by 1 type or in combination of 2 or more types.
Examples of antiseptics and fungicides include isothiazoline compounds, paraoxybenzoates, phenoxyethanol and the like.

It is preferable that the polishing composition disclosed here contains substantially no oxidizing agent. When an oxidizing agent is contained in the polishing composition, the composition is supplied to an object to be polished (for example, a silicon wafer), whereby the surface of the object to be polished is oxidized to produce an oxide film. This is because the polishing rate may decrease. Specific examples of the oxidizing agent herein include hydrogen peroxide (H ₂ O ₂ ), sodium persulfate, ammonium persulfate, sodium dichloroisocyanurate, and the like. In addition, that polishing composition does not contain an oxidizing agent substantially means not containing an oxidizing agent at least intentionally. Accordingly, a trace amount (for example, the molar concentration of the oxidizing agent in the polishing composition is 0.0005 mol / L or less, preferably 0.0001 mol / L or less, more preferably 0.00001, derived from the raw material, the manufacturing method, or the like. The polishing composition that inevitably contains an oxidizing agent of mol / L or less, particularly preferably 0.000001 mol / L or less) is a concept of a polishing composition that does not substantially contain an oxidizing agent here. Can be included.

<Polishing liquid>
The polishing composition disclosed herein is typically supplied to a polishing object in the form of a polishing liquid containing the polishing composition, and used for polishing the polishing object. The polishing liquid may be prepared, for example, by diluting (typically diluting with water) any of the polishing compositions disclosed herein. Or you may use this polishing composition as polishing liquid as it is. That is, the concept of the polishing composition in the technology disclosed herein is used as a polishing liquid diluted with a polishing liquid (working slurry) that is supplied to a polishing object and used for polishing the polishing object. Both concentrated liquid (polishing liquid stock solution) are included. Another example of the polishing liquid containing the polishing composition disclosed herein is a polishing liquid obtained by adjusting the pH of the composition.

  The content of abrasive grains in the polishing liquid disclosed herein is not particularly limited, but is typically 0.05% by weight or more, preferably 0.1% by weight or more, and 0.3% by weight or more. (For example, 0.5% by weight or more) is more preferable. Higher polishing rates can be achieved by increasing the abrasive content. Further, from the viewpoint of dispersion stability of the polishing composition, the content is usually suitably 10% by weight or less, preferably 7% by weight or less, more preferably 5% by weight or less, and still more preferably. 3% by weight or less.

  The pH of the polishing liquid is preferably 8.0 or more (for example, 8.5 or more), more preferably 9.0 or more, and further preferably 9.5 or more (for example, 10.0 or more). When the pH of the polishing liquid increases, the polishing rate tends to improve. The upper limit of the pH of the polishing liquid is not particularly limited, but is preferably 12.0 or less (for example, 11.5 or less), and more preferably 11.0 or less. As a result, the object to be polished can be better polished. The pH can be preferably applied to a polishing liquid used for polishing a silicon wafer. The pH of the polishing liquid is measured using a pH meter (for example, a glass electrode type hydrogen ion concentration indicator (model number F-23) manufactured by Horiba, Ltd.) and a standard buffer solution (phthalate pH buffer solution pH: 4.01 ( 25 ° C), neutral phosphate pH buffer solution pH: 6.86 (25 ° C), carbonate pH buffer solution pH: 10.01 (25 ° C)), and then the glass electrode It can be grasped by measuring the value after being put in the polishing liquid and stabilized after 2 minutes or more.

<Concentrate>
The polishing composition disclosed herein may be in a concentrated form (that is, in the form of a polishing liquid concentrate) before being supplied to the object to be polished. The polishing composition in such a concentrated form is advantageous from the viewpoints of convenience, cost reduction, etc. during production, distribution, storage and the like. The concentration ratio can be, for example, about 2 to 100 times in terms of volume, and usually about 5 to 50 times is appropriate. The concentration rate of the polishing composition according to a preferred embodiment is 10 to 40 times.

  Thus, the polishing composition in the form of a concentrated liquid can be used in such a manner that a polishing liquid is prepared by diluting at a desired timing and the polishing liquid is supplied to a polishing object. The dilution can be typically performed by adding and mixing the above-mentioned aqueous solvent to the concentrated solution. In addition, when the aqueous solvent is a mixed solvent, only a part of the components of the aqueous solvent may be added for dilution, and a mixture containing these components in a different ratio from the aqueous solvent. A solvent may be added for dilution. In addition, as will be described later, in a multi-component polishing composition, a part of them may be diluted and then mixed with another agent to prepare a polishing liquid, or a plurality of agents may be mixed. Later, the mixture may be diluted to prepare a polishing liquid.

  The content of abrasive grains in the concentrated liquid can be, for example, 50% by weight or less. From the viewpoint of the stability of the polishing composition (for example, dispersion stability of abrasive grains) and filterability, the content is usually preferably 45% by weight or less, more preferably 40% by weight or less. . In a preferred embodiment, the abrasive content may be 30% by weight or less, or 20% by weight or less (eg, 15% by weight or less). In addition, from the viewpoint of convenience in manufacturing, distribution, storage, etc. and cost reduction, the content of abrasive grains can be, for example, 0.5% by weight or more, preferably 1% by weight or more, and more preferably Is 3% by weight or more (for example, 4% by weight or more).

  The polishing composition disclosed herein may be a one-part type or a multi-part type including a two-part type. For example, the liquid A containing a part of the constituents of the polishing composition (typically, components other than the aqueous solvent) and the liquid B containing the remaining components are mixed to form a polishing object. You may be comprised so that it may be used for grinding | polishing.

<Preparation of polishing composition>
The manufacturing method of polishing composition disclosed here is not specifically limited. For example, each component contained in the polishing composition may be mixed using a well-known mixing device such as a blade-type stirrer, an ultrasonic disperser, or a homomixer. The aspect which mixes these components is not specifically limited, For example, all the components may be mixed at once and may be mixed in the order set suitably.

<Application>
The polishing composition disclosed herein can be applied to polishing a polishing object having various materials and shapes. The material of the object to be polished is, for example, a metal or semimetal such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, stainless steel, germanium, or an alloy thereof; quartz glass, aluminosilicate glass, glassy carbon, etc. A glassy substance; ceramic material such as alumina, silica, sapphire, silicon nitride, tantalum nitride, titanium carbide; compound semiconductor substrate material such as silicon carbide, gallium nitride, gallium arsenide; resin material such as polyimide resin; obtain. Of these, a polishing object composed of a plurality of materials may be used. Especially, it is suitable for grinding | polishing of the grinding | polishing target object provided with the surface which consists of silicon | silicone. The technique disclosed herein can be applied particularly preferably to a polishing composition that typically contains only silica particles as abrasive grains and whose polishing object is silicon.
The shape of the object to be polished is not particularly limited. The polishing composition disclosed herein can be preferably applied to a polishing object having a flat surface, such as a plate shape or a polyhedron shape, or polishing of an end portion of the polishing object (for example, polishing of a wafer edge).

<Polishing>
The polishing composition disclosed herein can be preferably used as a polishing composition for polishing a silicon substrate (for example, a monocrystalline or polycrystalline silicon wafer). Hereinafter, a preferred embodiment of a method for polishing a polishing object using the polishing composition disclosed herein will be described.
That is, a polishing liquid containing any of the polishing compositions disclosed herein is prepared. Preparing the polishing liquid may include preparing a polishing liquid by adding operations such as concentration adjustment (for example, dilution) and pH adjustment to the polishing composition. Or you may use the said polishing composition as polishing liquid as it is. Further, in the case of a multi-drug type polishing composition, to prepare the polishing liquid, mixing those agents, diluting one or more agents before the mixing, and after the mixing Diluting the mixture, etc. can be included.

  Next, the polishing liquid is supplied to the object to be polished and polished by a conventional method. For example, when performing a primary polishing process (typically a double-side polishing process) of a silicon substrate, the silicon substrate that has undergone the lapping process is set in a general polishing apparatus, and the silicon substrate is passed through the polishing pad of the polishing apparatus. A polishing liquid is supplied to the surface to be polished. Typically, while supplying the polishing liquid continuously, the polishing pad is pressed against the surface of the silicon substrate to be polished to relatively move (for example, rotate) the two. Thereafter, if necessary, a further secondary polishing step (typically a single-side polishing step) is performed, and finally final polishing is performed to complete polishing of the object to be polished.

  In addition, the polishing pad used in the polishing process using the polishing composition disclosed herein is not particularly limited. For example, any of non-woven fabric type, suede type, polyurethane type, those containing abrasive grains, and those not containing abrasive grains may be used.

According to this specification, the board | substrate manufacturing method including the process of grind | polishing a board | substrate using the polishing composition disclosed here is provided. The board | substrate manufacturing method disclosed here may further include the process of performing final polishing to the board | substrate which passed through the grinding | polishing process using the said polishing composition. Here, final polishing refers to the final polishing step in the manufacturing process of the object (that is, a step in which no further polishing is performed after that step). The final polishing step may be performed using the polishing composition disclosed herein, or may be performed using another polishing composition.
In a preferred embodiment, the substrate polishing step using the polishing composition is a polishing step upstream of the final polishing. Especially, it can apply preferably to the preliminary | backup polishing of the board | substrate which finished the lapping process. For example, a double-side polishing process (typically a primary polishing process) that has undergone a lapping process, or an initial single-side polishing process (typically an initial secondary polishing process) that is performed on a substrate that has undergone the double-side polishing process. Can be preferably used. In the double-side polishing step and the first single-side polishing step, a required polishing rate is larger than final polishing. Therefore, the polishing composition disclosed herein is suitable as a polishing composition used for polishing a substrate in at least one (preferably both) of the double-side polishing step and the first single-side polishing step.

  Hereinafter, some examples relating to the present invention will be described. However, the present invention is not intended to be limited to the examples. In the following description, “parts” and “%” are based on weight unless otherwise specified.

<Preparation of polishing composition>
(Examples 1-12, Comparative Examples 1-3)
Colloidal silica as an abrasive, N-aminoethylpiperazine (AEP) as a polishing accelerator, and pure water were mixed to prepare a polishing composition according to each example. The concentrations of the abrasive grains and the polishing accelerator are as shown in Table 1. As the abrasive grains, colloidal silica particles having secondary particle diameter (average secondary particle diameter) [nm], specific surface area [m ² / g], and aspect ratio shown in Table 1 were used. The pH of the polishing composition according to each example is adjusted to 10.3.
Moreover, about the polishing composition which concerns on each example, the total surface area A [m < ² > / kg composition] of the abrasive grain contained in 1 kg of polishing composition, and the total of the abrasive grain contained in 1 kg of polishing composition The ratio (A / B) of the total surface area A [m ² / kg composition] of the abrasive grains to the volume B [m ³ / kg composition] was determined. These values are shown in Table 1. In determining the ratio (A / B), 2.2 g / cm ³ (silica particle density) was used as the value of the abrasive density.

[Evaluation of polishing rate]
Using the polishing composition according to each example as a polishing liquid as it was, a polishing test was performed on the silicon wafer to evaluate the silicon polishing rate. A 60 mm × 60 mm silicon wafer (conductivity type: P type, crystal orientation: <100>, resistivity 0.1 Ω · cm or more and less than 100 Ω · cm) was used as a test piece. This specimen was polished under the following conditions. The polishing rate [μm / min] was calculated according to the following calculation formulas (1) and (2).
(1) Polishing allowance [cm] = silicon wafer weight difference before and after polishing [g] / silicon density [g / cm ³ ] (= 2.33 g / cm ³ ) / polishing target area [cm ² ] ( = 36cm ² )
(2) Polishing rate [μm / min] = polishing allowance [cm] × 10 ⁴ / polishing time (= 10 minutes)
[Polishing conditions]
Polishing apparatus: Single-side polishing apparatus manufactured by Nihon Engis Co., Ltd.
Polishing pad: Product name “MH S-15A”, manufactured by Nitta Haas
Polishing pressure: 250 g / cm ²
Surface plate rotation speed: 50 rotations / min. Head rotation speed: 50 rotations / min. Polishing time: 10 minutes. Polishing liquid supply rate: 100 mL / min.
Polishing liquid temperature: 25 ° C
The polishing rate [μm / min] calculated in each example was converted to a relative value with the value of Comparative Example 1 being 100. The results are shown in Table 1. In Table 1, it means that the higher the polishing rate, the higher the polishing rate.

[Evaluation of surface roughness]
The surface roughness Ra [nm] of the polished silicon wafer was measured using a non-contact fine shape measuring device (trade name “ZYGO New View 5010” manufactured by Zygo Corporation). The surface roughness Ra [nm] obtained in each example was converted to a relative value with the value of Comparative Example 1 being 100. The results are shown in Table 1. In Table 1, it means that surface quality was so favorable that the value of surface roughness Ra was small.

(Examples 13 to 17, Reference Examples 18 to 20 )
A polishing composition according to each example was prepared in the same manner as in Example 2 except that the polishing accelerator was changed to that shown in Table 2. In Table 2, BAPP is 1,4- (bisaminopropyl) piperazine, DBU is 1,8-diazabicyclo [5.4.0] undec-7-ene, and DBN is 1,5-diazabicyclo [4. .3.0] -5-nonene, NMP is N-methylpiperazine, NEP is N-ethylpiperazine, TMAH is tetramethylammonium hydroxide, and TEAH is tetraethylammonium hydroxide. About these Examples, it carried out similarly to Example 1, and evaluated polishing rate [micrometer / min] and surface roughness Ra [nm]. The values of the obtained polishing rate [μm / min] and surface roughness Ra [nm] are shown in Table 2 as converted into relative values with the value of Comparative Example 1 being 100, as in Table 1.
For the polishing composition according to each example, the total surface area A [m ² / kg composition] and the ratio (A / B) were determined in the same manner as in Example 1. These values are shown in Table 2.

As shown in Table 1, the ratio of the total surface area A [m ² / kg composition] of the abrasive grains to the total volume B [m ³ / kg composition] of abrasive grains contained in 1 kg of the polishing composition (A In Examples 1 to 12 using polishing liquid satisfying / B) of 7.0 × 10 ⁷ or more, Comparative Examples 1 to 1 using polishing liquid having the ratio (A / B) of less than 7.0 × 10 ⁷ . Compared to 3, the polishing rate was high and the surface roughness was low. Further, in Examples 1 to 9 using the polishing liquid satisfying the above ratio (A / B) of 9.0 × 10 ⁷ or more, the polishing rate is up to 140% or more of Comparative Example 1 while maintaining low surface roughness. Improved. Further, in Examples 1 to 6 in which the total surface area A [m ² / kg composition] was 400 or more, the polishing rate and the surface roughness were highly compatible.

  Moreover, as shown in Table 2, since the same result was obtained even if the type of the basic compound as the polishing accelerator was changed, the polishing composition satisfying the above ratio (A / B) was It is inferred that it is effective for various basic compounds. From these results, it is understood that AEP and BAPP are particularly preferable as the polishing accelerator.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

Claims (9)

A polishing composition used in a polishing process upstream of final polishing in polishing a silicon wafer,
Silica particles as abrasive grains, and a basic compound as a polishing accelerator,
The chelating agent content is 1 part by weight or less with respect to 100 parts by weight of the abrasive grains,
The basic compound is
The following general formula (A):

(Wherein, ^{X 1} is a hydrogen atom, an amino group or if .X ¹ representing the bond to the ^{C 1} atom represents a bond to ^{C 1} atom, .X ^{2 where H 1} atom is not present, is a hydrogen atom Represents an amino group, an aminoalkyl group, or a bond to the C ¹ atom, and when X ² represents a bond to the C ¹ atom, the C ¹ -N ¹ bond is a double bond and there is no H ² atom. l is an integer of 1 to 6, m is an integer of 1 to 4, and n is an integer of 0 to 4).
Including a compound represented by
The ratio (A / B) of the total surface area A [m ² / kg composition] of the abrasive grains to the total volume B [m ³ / kg composition] of abrasive grains contained in 1 kg of the polishing composition is 7 0.0 × 10 ⁷ or more,
Polishing composition whose total surface area A [m < ² > / kg composition] of the said abrasive grain is 194-2000. The polishing composition according to claim 1, wherein the ratio (A / B) is 9.0 × 10 ⁷ or more. The polishing composition according to claim 1 or 2, wherein the total surface area A [m ² / kg composition] of the abrasive grains is 400 or more.   Polishing composition as described in any one of Claims 1-3 whose pH is 8-12.   Polishing composition as described in any one of Claims 1-4 which does not contain an oxidizing agent substantially.   The polishing composition according to claim 1, wherein the silica particles are colloidal silica.   Polishing composition as described in any one of Claims 1-6 which does not contain an acetylene type surfactant.   The polishing composition according to any one of claims 1 to 7, wherein the content of the inorganic basic compound is less than 1 mol per kg of the abrasive grains.   The amount of the said polishing accelerator is a polishing composition as described in any one of Claims 1-8 which is 3 mol or less per kg of the said abrasive grains.