JP6618355B2 - Polishing liquid composition - Google Patents

Description

  The present disclosure relates to a polishing liquid composition containing cerium oxide particles, a semiconductor substrate manufacturing method and polishing method using the same, and a polishing liquid kit.

  The CMP (Chemical Mechanical Polishing) technology is a method in which the polishing substrate and the polishing pad are relatively moved while supplying the polishing liquid to these contact portions in a state where the surface of the substrate to be polished and the polishing pad are in contact with each other. This is a technique in which the surface unevenness portion of the substrate to be polished is chemically reacted and mechanically removed and flattened by being moved.

  At present, when performing planarization of an interlayer insulating film, formation of a shallow trench isolation structure (hereinafter also referred to as “element isolation structure”), formation of a plug and a buried metal wiring, etc. in a semiconductor element manufacturing process, CMP technology has become an essential technology. In recent years, the multi-layered and high-definition of semiconductor elements have progressed dramatically, and further improvements in the yield and throughput of semiconductor elements have been demanded. Along with this, with respect to the CMP process, there is a demand for polishing without scratches and at a higher speed. For example, in the formation process of the shallow trench isolation structure, the polishing selectivity of the polishing stopper film (for example, silicon nitride film) with respect to the film to be polished (for example, silicon oxide film) (in other words, the polishing stopper film of the polishing stopper film) with high polishing speed. It is desired to improve the selectivity of polishing (which is harder to polish than the film to be polished).

In Patent Document 1, as an abrasive used for forming an element isolation structure, cerium oxide particles, a dispersant, a free —COOM group, a phenolic OH group, a —SO ₃ M group, a —OSO ₃ H group, An additive selected from water-soluble organic small molecules having an anionic group such as —PO ₄ M ₂ group or —PO ₃ M ₂ group (M is a metal atom such as H, NH ₄ or Na, K), and water A CMP abrasive comprising:

Japanese Patent Application Laid-Open No. 2001-7060

  Examples of the abrasive grains include cerium oxide (hereinafter also referred to as “ceria”) particles. As the ceria particles used as the abrasive grains, for example, ceria particles having various shapes and sizes (hereinafter referred to as “ceria pulverized ceria obtained by baking and crushing cerium compounds such as cerium carbonate and cerium nitrate”). Widely used is also referred to as “amorphous ceria”. However, in polishing using polishing grains such as amorphous ceria, it has been a problem to improve polishing selectivity while ensuring a polishing rate.

  The present disclosure provides a polishing liquid composition capable of ensuring a polishing rate and improving polishing selectivity, a semiconductor substrate manufacturing method and polishing method using the same, and a polishing liquid kit.

  The present disclosure is a polishing composition comprising cerium oxide particles A and water, wherein the zeta potential is −90 mV or more and less than 0 mV, and the concave index of the cerium oxide particles A is 1.000 or more. It is 1.035 or less, and the said recessed part index | exponent is related with the polishing liquid composition which is an average value of ratio (S / L) of the perimeter length S of the said particle | grains A, and the envelope perimeter length L.

The present disclosure is a polishing composition comprising cerium oxide particles A, water, and an anionic group-containing compound B, wherein the concave index of the cerium oxide particles A is 1.000 or more and 1. 035 or less, and the content of the compound B is 6.0 × 10 ⁻⁵ g / m ² or more and 3.8 × 10 ⁻¹ g / m ² or less with respect to the surface area of the cerium oxide particles A, The concave index relates to a polishing composition which is an average value of the ratio (S / L) of the peripheral length S of the particle A to the envelope peripheral length L.

  The present disclosure relates to a method for manufacturing a semiconductor substrate including a step of polishing a substrate to be polished using the polishing composition according to the present disclosure.

  The present disclosure relates to a method for polishing a substrate, including a step of polishing a substrate to be polished using the polishing composition according to the present disclosure, wherein the substrate to be polished is a substrate used for manufacturing a semiconductor substrate.

  The present disclosure is a slurry containing cerium oxide particles A and water, wherein the recess index of the cerium oxide particles A is 1.000 or more and 1.035, and the recess index of the particles A is It is related with the cerium oxide slurry used for manufacture of polishing liquid composition which is an average value of ratio (S / L) of perimeter length S and envelope perimeter length L.

  The present disclosure is a kit for producing a polishing liquid composition, including a container-containing particle A dispersion in which a dispersion containing cerium oxide particles A is contained in a container, and the concave index of the cerium oxide particles A However, the concave index is related to the polishing liquid kit, which is an average value of the ratio (S / L) of the peripheral length S of the particles A to the envelope peripheral length L.

  According to the present disclosure, it is possible to provide an effect that it is possible to provide a polishing liquid composition capable of ensuring a polishing rate and improving polishing selectivity.

FIG. 1 is a schematic diagram for explaining the peripheral length S and the envelope peripheral length L of a particle. FIG. 2 is an example of a transmission electron microscope (hereinafter also referred to as “TEM”) observation photograph of ceria particles having a recess index of 1.017. FIG. 3 is an example of a TEM observation photograph of ceria particles having a recess index of 1.042.

  As a result of intensive studies by the present inventors, in a polishing liquid composition containing ceria particles as abrasive grains, surprisingly, the number of concave portions of ceria particles is reduced, and the zeta potential of the polishing liquid composition is set to a negative specific value. As a result, it was found that the polishing selectivity was improved while ensuring the polishing rate, and the present invention was completed.

  In the polishing liquid composition containing ceria particles as abrasive grains, the present disclosure specifies a shape of the ceria particles and a compound having a negative specific value for the zeta potential of the polishing liquid composition or having an anionic group. It is based on the knowledge that, by using in combination, it is possible to ensure the polishing rate and improve the polishing selectivity.

  In the present disclosure, “polishing selectivity” is synonymous with the ratio of the polishing rate of the film to be polished to the polishing rate of the polishing stopper film (polishing rate of the film to be polished / polishing rate of the polishing stopper film). A high value means that the polishing rate ratio is large.

The present disclosure is a polishing composition comprising cerium oxide particles A and water, wherein the zeta potential is −90 mV or more and less than 0 mV, and the concave index of the cerium oxide particles A is 1.000 or more. It is 1.035 or less, and the said recessed part index | exponent is related with the polishing liquid composition which is an average value of ratio (S / L) of the perimeter length S of the said particle | grains A, and the envelope perimeter length L. Furthermore, the present disclosure provides a polishing composition comprising cerium oxide particles A, water, and a compound B having an anionic group, wherein the concave index of the cerium oxide particles A is 1.000 or more. 1.035 or less, and the content of the compound B is 6.0 × 10 ⁻⁵ g / m ² or more and 3.8 × 10 ⁻¹ g / m ² or less with respect to the surface area of the cerium oxide particles A. In addition, the concave index relates to a polishing composition, which is an average value of the ratio (S / L) of the peripheral length S and the envelope peripheral length L of the particles A. According to the polishing composition according to the present disclosure, it is possible to ensure the polishing rate and improve the polishing selectivity.

[Cerium oxide particles A]
The polishing composition according to the present disclosure contains cerium oxide particles A (hereinafter also simply referred to as “particles A”) as polishing abrasive grains. The particles A can be produced, for example, by a sedimentation method. As the sedimentation method, for example, a method described in JP-T-2010-505735 can be employed.

  The concave index of the particle A is 1.000 or more, preferably 1.010 or more, more preferably 1.015 or more, and 1.035 or less from the viewpoint of improving the polishing rate, and 1.030 or less. The following is preferable, 1.025 or less is more preferable, and 1.020 or less is still more preferable. In the present disclosure, the concave index of the particle A refers to an average value of the ratio (S / L) of the peripheral length S and the envelope peripheral length L of the particle A, which is obtained by analyzing a projection image using an electron microscope or the like. It shows that there are few recessed parts on the surface of the particle | grain A, so that the value of a recessed part index | exponent is small. For example, in the case of a particle having a shape as shown in FIG. 1, the peripheral length S of the particle indicates a length calculated along the contour of the particle, and the envelope peripheral length L of the particle indicates the contour of the particle. This indicates the perimeter of a polygon having the same number of vertices as the convex portion and enclosing all the contours of the particle (that is, a polygon in which all the convex portions of the particle contour are inscribed).

  The zeta potential of the particles A in the aqueous medium is usually positive, but is preferably negative from the viewpoints of ensuring the polishing rate, improving the polishing selectivity, and reducing the residual abrasive grains. As a method of making the zeta potential in the aqueous medium of the particles A negative, for example, a method of adding a compound B having an anionic group described later into the polishing composition can be mentioned. When the polishing liquid composition according to the present disclosure contains a predetermined amount of the compound B having an anionic group, the compound B acts on the particle A, and the zeta potential of the particle A in the aqueous medium can be made negative. In this case, the zeta potential of the particles A in the aqueous medium is preferably less than 0 mV, more preferably −30 mV or less, more preferably from the viewpoint of ensuring the polishing rate, improving the polishing selectivity, and reducing the residual abrasive grains. Preferably it is −60 mV or less, preferably −90 mV or more, more preferably −80 mV or more, and further preferably −70 mV.

The average primary particle diameter of the particles A is preferably 15 nm or more, more preferably 20 nm or more, and further preferably 40 nm or more from the viewpoint of improving the polishing rate, and preferably 300 nm or less from the viewpoint of suppressing the generation of polishing flaws. More preferably, it is 200 nm or less, More preferably, it is 150 nm or less. In the present disclosure, the average primary particle size of the particles A is calculated using a BET specific surface area S (m ² / g) calculated by a BET (nitrogen adsorption) method. The BET specific surface area can be measured by the method described in Examples.

  The shape of the particles A is preferably a shape having few concave portions on the surface from the viewpoint of improving the polishing rate, and examples thereof include a substantially spherical shape and a polyhedral shape. Examples of the particles A include polyhedral ceria as shown in FIG.

  The content of the particles A in the polishing liquid composition according to the present disclosure is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, from the viewpoint of ensuring the polishing rate and improving the polishing selectivity. More preferably, it is 0.05% by mass or more, and preferably 1.0% by mass or less, more preferably 0.80% by mass or less, and still more preferably 0.60% by mass or less.

[Compound B]
The polishing composition according to the present disclosure preferably contains Compound B having an anionic group as a polishing aid from the viewpoints of ensuring a polishing rate, improving polishing selectivity, and reducing residual abrasive grains. Compound B makes the zeta potential of the polishing liquid composition negative, adsorbs on the surface of the particle A to make the zeta potential of the particle A negative, or makes the zeta potential of the polishing liquid composition and the particle A negative. It is possible to

  Examples of the anionic group of Compound B include a carboxylic acid group, a sulfonic acid group, a sulfate ester group, a phosphate ester group, and a phosphonic acid group. These anionic groups may take the form of neutralized salts. Examples of the counter ion when the anionic group is in the form of a salt include a metal ion, an ammonium ion, an alkylammonium ion, and the like. From the viewpoint of improving the quality of the semiconductor substrate, an ammonium ion is preferable.

  As compound B, an anionic polymer is mentioned, for example. Specific examples of compound B include polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, a copolymer of (meth) acrylic acid and monomethoxypolyethylene glycol mono (meth) acrylate, (meth) acrylate having an anionic group, Copolymers of monomethoxypolyethylene glycol mono (meth) acrylate, copolymers of alkyl (meth) acrylate, (meth) acrylic acid and monomethoxypolyethylene glycol mono (meth) acrylate, alkali metal salts thereof, and these From the viewpoint of improving the quality of the semiconductor substrate, at least one selected from polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, and these ammonium salts is preferable.

  The weight average molecular weight of Compound B is preferably 1000 or more, more preferably 10,000 or more, still more preferably 20000 or more, from the viewpoints of ensuring the polishing rate, improving the polishing selectivity, and reducing the residual abrasive grains. Preferably it is 5.5 million or less, More preferably, it is 1 million or less, More preferably, it is 100,000 or less.

In the present disclosure, the weight average molecular weight can be measured by gel permeation chromatography (GPC) using liquid chromatography (manufactured by Hitachi, Ltd., L-6000 type high performance liquid chromatography) under the following conditions.
Detector: Shodex RI SE-61 differential refractive index detector Column: G4000PWXL and G2500PWXL manufactured by Tosoh Corporation were connected in series.
Eluent: 0.2 M phosphate buffer / acetonitrile = 90/10 (volume ratio) was adjusted to a concentration of 0.5 g / 100 mL, and 20 μL was used.
Column temperature: 40 ° C
Flow rate: 1.0 mL / min
Standard polymer: Monodispersed polyethylene glycol with known molecular weight

  The content of Compound B in the polishing liquid composition according to the present disclosure is preferably 0.001% by mass or more, more preferably, from the viewpoints of ensuring a polishing rate, improving polishing selectivity, and reducing residual abrasive grains. 0.01% by mass or more, more preferably 0.1% by mass or more, and preferably 1.0% by mass or less, more preferably 0.8% by mass or less, still more preferably 0.6% by mass or less. is there.

  The mass ratio (B / A) between the particles A and the compounds B in the polishing composition according to the present disclosure is preferably 0 from the viewpoints of securing the polishing rate, improving the polishing selectivity, and reducing the residual abrasive grains. 0.002 or more, more preferably 0.02 or more, still more preferably 0.2 or more, and preferably 2.0 or less, more preferably 1.6 or less, and even more preferably 1.1 or less.

The content of Compound B in the polishing liquid composition according to the present disclosure is 6.0 × with respect to the surface area of the particles A from the viewpoint of ensuring the polishing rate, improving the polishing selectivity, and reducing the residual abrasive grains. 10 ⁻⁵ g / m ² or more is preferable, 2.1 × 10 ⁻⁴ g / m ² or more is more preferable, 5.1 × 10 ⁻⁴ g / m ² or more is more preferable, and 3.8 × 10 ⁻¹ g / m ² or less is preferable, 1.8 × 10 ⁻¹ g / m ² or less is more preferable, and 1.3 × 10 ⁻¹ g / m ² or less is more preferable. In the present disclosure, the content of the compound B is represented by a ratio of the weight of the compound B to the total surface area of the contained particles A ([weight of the compound B] / [total surface area of the particle A]). The total surface area of the particles A can be calculated by multiplying the specific surface area S (m ² / g) calculated by the BET (nitrogen adsorption) method by the content of ceria particles in the polishing liquid composition according to the present disclosure.

[water]
The polishing liquid composition according to the present disclosure contains water as a medium. The water is more preferably water such as ion-exchanged water, distilled water or ultrapure water from the viewpoint of improving the quality of the semiconductor substrate. The content of water in the polishing liquid composition according to the present disclosure is as follows: Particle A, Compound B, Compound B added as necessary, and the total of the following optional components: 100% by mass. It can be set as the remainder except arbitrary components.

[Other ingredients]
The polishing liquid composition according to the present disclosure can contain other components as long as the effects of ensuring the polishing rate and improving the polishing selectivity are not impaired. Examples of other components include pH adjusters and polishing aids other than Compound B. Furthermore, examples of other components include a thickener, a dispersant, a rust inhibitor, a basic substance, a polishing rate improver, a surfactant, and a polymer compound. The content of these optional components is preferably 0.001% by mass or more, more preferably 0.0025% by mass or more, still more preferably 0.01% by mass or more, from the viewpoint of securing the polishing rate of the film to be polished. From the viewpoint of improving selectivity, it is preferably 1% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.1% by mass or less.

  Examples of the pH adjuster include acidic compounds and alkali compounds. Examples of the acidic compound include inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid; organic acids such as acetic acid, oxalic acid, citric acid, and malic acid; Among these, from the viewpoint of versatility, at least one selected from hydrochloric acid, nitric acid and acetic acid is preferable, and at least one selected from hydrochloric acid and acetic acid is more preferable. Examples of the alkali compound include inorganic alkali compounds such as ammonia and potassium hydroxide; organic alkali compounds such as alkylamine and alkanolamine; and the like. Among these, from the viewpoint of improving the quality of the semiconductor substrate, at least one selected from ammonia and alkylamine is preferable, and ammonia is more preferable.

  Examples of the polishing aid other than the compound B include anionic surfactants and nonionic surfactants. Examples of the anionic surfactant include anionic monomers such as polyacrylic acid, alkyl ether acetates, alkyl ether phosphates, and alkyl ether sulfates. Examples of nonionic surfactants include nonionic polymers such as polyacrylamide, and polyoxyalkylene alkyl ethers.

[Polishing liquid composition]
The polishing liquid composition according to the present disclosure can be produced by a production method including a slurry containing particles A and water and, if desired, a compound B and other optional components by a known method. For example, the polishing liquid composition according to the present disclosure is formed by blending particles A and water, and optionally compound B and other optional components. Therefore, this indication is related with the cerium oxide slurry (henceforth the slurry concerning this indication) used for manufacture of polish composition which contains particles A and water. And the slurry concerning this indication can contain compound B. In the present disclosure, “compounding” includes mixing the particles A and water, and optionally the compound B and other optional components simultaneously or sequentially. The order of mixing is not particularly limited. The said mixing | blending can be performed using mixers, such as a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill, for example. The compounding quantity of each component in the manufacturing method of the polishing liquid composition which concerns on this indication can be made the same as content of each component in the polishing liquid composition which concerns on this indication mentioned above.

  The embodiment of the polishing composition according to the present disclosure may be a so-called one-component type that is supplied to the market in a state where all components are mixed in advance, or may be a so-called two-component type that is mixed at the time of use. It may be. The two-component type polishing liquid composition is divided into a first liquid and a second liquid. For example, the polishing liquid composition includes a first liquid in which particles A are mixed in water, and a compound B dissolved in water. It is comprised from the made 2nd liquid, and a 1st liquid and a 2nd liquid may be mixed. The mixing of the first liquid and the second liquid may be performed before supply to the surface to be polished, or these may be supplied separately and mixed on the surface of the substrate to be polished.

  The pH of the polishing composition according to the present disclosure is preferably 2.5 or more, more preferably 3.0 or more, still more preferably 3.5 or more, from the viewpoint of ensuring the polishing rate and improving the polishing selectivity. More preferably 4.0 or more, still more preferably 5.5 or more, and preferably 8.5 or less, more preferably 8.0 or less, and still more preferably 7.5 or less. In the present disclosure, the pH of the polishing composition is a value at 25 ° C. and is a value measured using a pH meter. Specifically, the pH of the polishing composition in the present disclosure can be measured by the method described in Examples.

  The zeta potential of the polishing composition according to the present disclosure is preferably negative (less than 0 mV), more preferably −51 mV or less, further preferably, from the viewpoints of ensuring a polishing rate, improving polishing selectivity, and reducing residual abrasive grains. Is −70 mV or less, more preferably −75 mV or less, more preferably −77 mV or less, further preferably −78 mV or less, and preferably −90 mV or more, more preferably −85 mV or more, and further preferably −82 mV or more. More preferably, it is −80 mV or more.

  In the present disclosure, “content of each component in the polishing liquid composition” refers to the content of each component at the time when the polishing liquid composition is used for polishing. The polishing composition according to the present disclosure may be stored and supplied in a concentrated state as long as its stability is not impaired. In this case, it is preferable in that the manufacturing / transportation cost can be reduced. This concentrated liquid can be appropriately diluted with the above-mentioned aqueous medium as necessary and used in the polishing step. The dilution ratio is preferably 5 to 100 times.

[Polished film]
An example of a film to be polished by the polishing liquid composition according to the present disclosure includes a silicon oxide film. Therefore, the polishing liquid composition according to the present disclosure can be suitably used for polishing performed in the step of forming an element isolation structure of a semiconductor substrate.

[Polishing liquid kit]
The present disclosure relates to a polishing liquid kit for producing a polishing liquid composition, which includes a container-containing particle A dispersion in which a dispersion containing the particles A is contained in a container. The polishing liquid kit according to the present disclosure may further include the compound B stored in a container different from the container-containing particle A dispersion. According to the present disclosure, it is possible to provide a polishing liquid kit from which a polishing liquid composition capable of ensuring a polishing rate and improving polishing selectivity can be obtained.

  The polishing liquid kit according to the present disclosure includes, for example, a solution (first liquid) containing the particles A and a solution (first liquid) that can be blended in a polishing liquid composition used for polishing an object to be polished. 2 liquid) is stored in a state where they are not mixed with each other, and a polishing liquid kit (2 liquid type polishing liquid composition) in which these are mixed at the time of use is mentioned. Examples of other components that can be blended in the polishing liquid composition include compound B, acid, oxidizing agent, heterocyclic aromatic compound, aliphatic amine compound, and alicyclic amine compound. The first liquid and the second liquid may each contain an optional component as necessary. Examples of the optional component include a thickener, a dispersant, a rust inhibitor, a basic substance, a polishing rate improver, a surfactant, and a polymer compound.

[Method for Manufacturing Semiconductor Substrate]
The present disclosure includes a step of polishing a film to be polished using the polishing liquid composition according to the present disclosure (hereinafter, also referred to as “polishing step using the polishing liquid composition according to the present disclosure”). The present invention relates to a method (hereinafter also referred to as “a method of manufacturing a semiconductor substrate according to the present disclosure”). According to the method for manufacturing a semiconductor substrate according to the present disclosure, it is possible to improve the polishing selectivity while ensuring the polishing rate in the polishing step. Therefore, it is possible to achieve an effect that a semiconductor substrate with improved substrate quality can be efficiently manufactured.

As a specific example of the method of manufacturing a semiconductor substrate according to the present disclosure, first, a silicon dioxide layer is grown on the surface of the silicon substrate by exposing the silicon substrate to oxygen in an oxidation furnace, and then silicon nitride ( A polishing stopper film such as a Si ₃ N ₄ ) film or a polysilicon film is formed by, for example, a CVD method (chemical vapor deposition method). Next, a photolithography technique is applied to a substrate including a silicon substrate and a polishing stopper film disposed on one main surface side of the silicon substrate, for example, a substrate in which a polishing stopper film is formed on a silicon dioxide layer of a silicon substrate. Is used to form a trench. Next, a silicon oxide (SiO ₂ ) film, which is a film to be polished for trench filling, is formed by, for example, a CVD method using silane gas and oxygen gas, and the polishing stopper film is covered with the film to be polished (silicon oxide film). A polished substrate is obtained. By forming the silicon oxide film, the trench is filled with silicon oxide of the silicon oxide film, and the surface opposite to the surface of the polishing stopper film on the silicon substrate side is covered with the silicon oxide film. The surface opposite to the surface on the silicon substrate side of the silicon oxide film thus formed has a step formed corresponding to the unevenness of the lower layer. Next, the silicon oxide film is polished by CMP until at least the opposite surface of the surface of the polishing stopper film on the silicon substrate side is exposed. More preferably, the surface of the silicon oxide film and the surface of the polishing stopper film are flush with each other. The silicon oxide film is polished until The polishing composition according to the present disclosure can be used in the step of polishing by the CMP method.

  In polishing by the CMP method, the surface of the substrate to be polished and the polishing pad are in contact with each other, and the polishing substrate composition and the polishing pad are relatively moved while supplying the polishing composition according to the present disclosure to these contact portions. By doing so, the uneven portions on the surface of the substrate to be polished are flattened. In the method for manufacturing a semiconductor substrate according to the present disclosure, another insulating film may be formed between the silicon dioxide layer of the silicon substrate and the polishing stopper film, or the polishing target film (for example, a silicon oxide film) and the polishing may be performed. Another insulating film may be formed between the stopper film.

In the polishing step using the polishing composition according to the present disclosure, the number of rotations of the polishing pad is, for example, 30 to 200 r / min, and the number of rotations of the substrate to be polished is, for example, 130 to 200 r / min. The polishing load set in the polishing apparatus can be set to, for example, 20 to 500 g weight / cm ² , and the supply rate of the polishing composition can be set to, for example, 10 to 500 mL / min or less. When the polishing liquid composition is a two-part polishing liquid composition, the respective polishing speeds of the film to be polished and the polishing stopper film are adjusted by adjusting the respective supply speeds (or supply amounts) of the first liquid and the second liquid. In addition, the polishing rate ratio (polishing selectivity) between the film to be polished and the polishing stopper film can be adjusted.

  In the polishing step using the polishing composition according to the present disclosure, the polishing time is preferably 10 seconds or more, more preferably 20 seconds or more, from the viewpoint of improving polishing selectivity, and from the viewpoint of improving productivity. , Preferably 3 minutes or less, more preferably 2 minutes or less, still more preferably 1 minute or less.

  In the polishing step using the polishing liquid composition according to the present disclosure, the polishing rate of the film to be polished (for example, a silicon oxide film) is preferably 600 nm / min or less, more preferably 500 nm / min, from the viewpoint of improving polishing selectivity. In the following, it is more preferably 400 nm / min or less, and from the viewpoint of improving productivity, it is preferably 30 nm / min or more, more preferably 50 nm / min or more, and further preferably 100 nm / min or more.

  In the polishing process using the polishing composition according to the present disclosure, the polishing rate of the polishing stopper film (for example, silicon nitride film) is preferably 80 nm / min or less from the viewpoint of improving the polishing selectivity and shortening the polishing time. More preferably, it is 40 nm / min or less, and further preferably 15 nm / min or less.

  In the polishing step using the polishing composition according to the present disclosure, the polishing rate ratio (polishing rate of the film to be polished / polishing rate of the polishing stopper film) is preferably 4.8 or more from the viewpoint of shortening the polishing time. More preferably, it is 10.0 or more, More preferably, it is 20.0 or more. In the present disclosure, the polishing selectivity is synonymous with the ratio of the polishing rate of the film to be polished to the polishing rate of the polishing stopper (polishing rate of the film to be polished / polishing rate of the polishing stopper film), and high polishing selectivity means This means that the polishing rate ratio is large.

[Polishing method]
The present disclosure relates to a substrate polishing method (hereinafter, also referred to as a polishing method according to the present disclosure) including a polishing step using the polishing composition according to the present disclosure.

  By using the polishing method according to the present disclosure, it is possible to improve the polishing selectivity while ensuring the polishing rate in the polishing step, and thus the effect that the productivity of the semiconductor substrate with improved substrate quality can be improved. Specific polishing methods and conditions can be the same as those of the semiconductor substrate manufacturing method according to the present disclosure described above.

  The present disclosure further relates to the following compositions and production methods.

<1> A polishing composition comprising cerium oxide particles A and water,
The zeta potential is −90 mV or more and less than 0 mV,
The concave index of the cerium oxide particles A is 1.000 or more and 1.035 or less,
The concave portion index is a polishing liquid composition that is an average value of the ratio (S / L) of the peripheral length S of the particle A to the envelope peripheral length L.

<2> The polishing composition according to <1>, preferably further containing a compound B having an anionic group.
<3> The content of the compound B is 6.0 × 10 ⁻⁵ g / m ² or more and 3.8 × 10 ⁻¹ g / m ² or less with respect to the surface area of the cerium oxide particles A. <2> The polishing liquid composition as described in 2. above.
<4> A polishing composition comprising at least cerium oxide particles A, water, and a compound B having an anionic group,
The concave index of the cerium oxide particles A is 1.000 or more and 1.035 or less,
The content of the compound B is 6.0 × 10 ⁻⁵ g / m ² or more and 3.8 × 10 ⁻¹ g / m ² or less with respect to the surface area of the cerium oxide particles A,
The concave portion index is a polishing liquid composition that is an average value of the ratio (S / L) of the peripheral length S of the particle A to the envelope peripheral length L.
<5> The polishing liquid according to any one of <2> to <4>, wherein compound B is preferably at least one selected from polyacrylic acid ammonium salt, polymethacrylic acid ammonium salt, and polystyrenesulfonic acid ammonium salt. Composition.
<6> The polishing composition according to any one of <2> to <5>, wherein the compound B has a weight average molecular weight of preferably 1000 or more, more preferably 10,000 or more, and still more preferably 20000 or more.
<7> The polishing composition according to any one of <2> to <6>, wherein the compound B has a weight average molecular weight of preferably 5.5 million or less, more preferably 1,000,000 or less, and even more preferably 100,000 or less. .
<8> The content of Compound B is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.1% by mass or more. Any one of <2> to <7> A polishing liquid composition according to claim 1.
<9> The content of Compound B is preferably 1.0% by mass or less, more preferably 0.8% by mass or less, and still more preferably 0.6% by mass or less. Any one of <2> to <8> A polishing liquid composition according to claim 1.
<10> The mass ratio (B / A) between the particles A and the compound B is preferably 0.002 or more, more preferably 0.02 or more, and still more preferably 0.2 or more. <2> to <9 > The polishing liquid composition in any one of>.
<11> The mass ratio (B / A) between the particles A and the compound B is preferably 2.0 or less, more preferably 1.6 or less, and even more preferably 1.1 or less. <2> to <10 > The polishing liquid composition in any one of>.
<12> The content of the compound B is preferably 6.0 × 10 ⁻⁵ g / m ² or more, more preferably 2.1 × 10 ⁻⁴ g / m ² or more with respect to the surface area of the particles A. The polishing composition according to any one of <2> to <11>, which is more preferably 1 × 10 ⁻⁴ g / m ² or more.
<13> The content of the compound B is preferably 3.8 × 10 ⁻¹ g / m ² or less, more preferably 1.8 × 10 ⁻¹ g / m ² or less with respect to the surface area of the particles A. The polishing composition according to any one of <2> to <12>, more preferably 3 × 10 ⁻¹ g / m ² or less.
<14> The polishing composition according to any one of <1> to <13>, wherein the concave index of the particle A is 1,000 or more, preferably 1.010 or more, and more preferably 1.015 or more.
<15> The concave index of the particle A is 1.035 or less, preferably 1.030 or less, more preferably 1.025 or less, and further preferably 1.020 or less, any one of <1> to <14> The polishing liquid composition as described in 2. above.
<16> The polishing according to any one of <1> to <15>, wherein the zeta potential of the particles A in the aqueous medium is preferably less than 0 mV, more preferably -30 mV or less, and still more preferably -60 mV or less. Liquid composition.
<17> The polishing according to any one of <1> to <16>, wherein the zeta potential of the particle A in the aqueous medium is preferably −90 mV or more, more preferably −80 mV or more, and further preferably −70 mV. Liquid composition.
<18> The polishing composition according to any one of <1> to <17>, wherein the average primary particle diameter of the particles A is preferably 15 nm or more, more preferably 20 nm or more, and still more preferably 40 nm or more.
<19> The polishing composition according to any one of <1> to <18>, wherein the average primary particle diameter of the particles A is preferably 300 nm or less, more preferably 200 nm or less, and even more preferably 150 nm or less.
<20> The content of the particles A is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.05% by mass or more. Any one of <1> to <19> A polishing liquid composition according to claim 1.
<21> The content of the particles A is preferably 1.0% by mass or less, more preferably 0.80% by mass or less, and still more preferably 0.60% by mass or less. The polishing composition according to any one of <1> to <20>.
<22> The pH is preferably 2.5 or more, more preferably 3.0 or more, still more preferably 3.5 or more, still more preferably 4.0 or more, and even more preferably 5.5 or more. The polishing composition according to any one of <1> to <21>.
<23> The polishing composition according to any one of <1> to <22>, wherein the pH is preferably 8.5 or less, more preferably 8.0 or less, and even more preferably 7.5 or less.
<24> The polishing composition according to any one of <1> to <23>, wherein the pH is preferably 2.5 or more and 8.5 or less.
<25> The zeta potential of the polishing composition is preferably negative (less than 0 mV), more preferably -51 mV or less, still more preferably -70 mV or less, still more preferably -75 mV or less, still more preferably -77 mV or less, and even more preferably. Is a polishing composition according to any one of <1> to <24>, which is −78 mV or less.
<26> The zeta potential of the polishing composition is preferably −90 mV or more, more preferably −85 mV or more, still more preferably −82 mV or more, and further preferably −80 mV or more. Any of <1> to <27> A polishing liquid composition according to claim 1.
<27> A slurry containing cerium oxide particles A and water,
The concave index of the cerium oxide particles A is 1.000 or more and 1.035,
The said recessed index is a cerium oxide slurry used for manufacture of polishing liquid composition which is an average value of ratio (S / L) of perimeter length S of this particle A, and envelope perimeter length L.
<28> The slurry according to <27>, further preferably containing a compound B having an anionic group.
<29> A method for producing a semiconductor substrate, comprising a step of polishing a substrate to be polished using the polishing composition according to any one of <1> to <26>.
<30> The method for producing a semiconductor substrate according to <29>, wherein the polishing time is preferably 10 seconds or longer, more preferably 20 seconds or longer.
<31> The method for producing a semiconductor substrate according to <29> or <30>, wherein the polishing time is preferably 3 minutes or less, more preferably 2 minutes or less, and still more preferably 1 minute or less.
<32> The semiconductor according to any one of <29> to <31>, wherein the polishing rate of the film to be polished is preferably 600 nm / min or less, more preferably 500 nm / min or less, and still more preferably 400 nm / min or less. A method for manufacturing a substrate.
<33> The semiconductor according to any one of <29> to <32>, wherein the polishing rate of the film to be polished is preferably 30 nm / min or more, more preferably 50 nm / min or more, and further preferably 100 nm / min or more. A method for manufacturing a substrate.
<34> The semiconductor according to any one of <29> to <33>, wherein the polishing rate of the polishing stopper film is preferably 80 nm / min or less, more preferably 40 nm / min or less, and further preferably 15 nm / min or less. A method for manufacturing a substrate.
<35> The polishing rate ratio (polishing rate of the film to be polished / polishing rate of the polishing stopper film) is preferably 4.8 or more, more preferably 10.0 or more, still more preferably 20.0 or more, <29 > To <34>. A method for producing a semiconductor substrate according to any one of <34>.
<36> including a step of polishing a substrate to be polished using the polishing composition according to any one of <1> to <26>, wherein the substrate to be polished is a substrate used for manufacturing a semiconductor substrate. A method for polishing a substrate.
<37> A kit for producing a polishing composition,
A dispersion containing cerium oxide particles A includes a container-containing particle A dispersion stored in a container;
The concave index of the cerium oxide particles A is 1.000 or more and 1.035 or less,
The concave index is an average value of the ratio (S / L) of the peripheral length S of the particle A to the envelope peripheral length L.
Polishing fluid kit.
<38> The polishing liquid kit according to <37>, preferably further comprising a compound B having an anionic group housed in a container different from the container-containing particle A dispersion.

1. Preparation of Polishing Liquid Composition The polishing liquids of Examples 1 to 11 and Comparative Examples 1 to 6 were prepared by mixing water, abrasive grains (particles A), and additives (compound B) so as to have the contents shown in Table 1 below. A composition was obtained. The pH of the polishing composition was adjusted using a 1N hydrochloric acid aqueous solution or a 1N ammonium aqueous solution. The pH of the polishing composition of Examples 1 to 11 and Comparative Examples 1 to 6 was 6.

As the particle A, the following ceria particles were used.
Particle A1: Recess index 1.017, average primary particle size 82 nm, BET specific surface area 10.2 m ² / g (see FIG. 2)
Particle A2: Recess index 1.025, average primary particle size 82 nm, BET specific surface area 10.5 m ² / g
Particle A3: Recess index 1.042, average primary particle size 70 nm, BET specific surface area 11.8 m ² / g (see FIG. 3)

As the additive (compound B), the following compounds were used.
Compound B1: polyacrylic acid ammonium salt (weight average molecular weight 23,000)
Compound B2: polymethacrylic acid ammonium salt (weight average molecular weight 30,000)
Compound B3: polystyrene sulfonate ammonium salt (weight average molecular weight 10,000)
Compound B4: polydiallyldimethylammonium chloride (weight average molecular weight 5,000)
Compounds B1 to B3 are compounds having an anionic group.

  The pH and zeta potential of the polishing composition, the average primary particle size of the particles A, the BET specific surface area, and the recess index were measured by the following methods.

(A) Measurement of pH of polishing liquid composition The pH value at 25 ° C of the polishing liquid composition is a value measured using a pH meter (Toa Denki Kogyo Co., Ltd., HM-30G). It is a numerical value 1 minute after immersion in the water.

(B) Average primary particle size of particle A The average primary particle size (nm) of particle A is the specific surface area S (m ² / g) obtained by the following BET (nitrogen adsorption) method, and the true density of ceria particles is It was calculated as 7.2 g / cm ³ .

(C) Method for Measuring BET Specific Surface Area of Particle A The specific surface area was obtained by crushing ceria particle A dispersion at 120 ° C. for 3 hours with hot air and then finely pulverizing it in an agate mortar. Immediately before the measurement, the sample was dried for 15 minutes in an atmosphere of 120 ° C., and then measured by a nitrogen adsorption method (BET method) using a specific surface area measuring device (Micromeritic automatic specific surface area measuring device Flowsorb III 2305, manufactured by Shimadzu Corporation).

(D) Concave Index of Particle A The envelope peripheral length and peripheral length of the primary particles of the particle A were measured using an image obtained by an electron microscope (“S-4800” manufactured by Hitachi, Ltd.). The envelope perimeter was calculated from the perimeter of a polygon having the same number of vertices as the convex portion of the contour of the primary particle of particle A using image analysis software (WinROOF 2013 manufactured by Mitani Corporation). . The measurement was performed on 50 particles A, and the average value of the ratio of the peripheral length to the envelope peripheral length (perimeter length / envelope peripheral length) was defined as the recess index. It shows that there are few recessed parts in the surface of the primary particle of the particle | grains A, so that the value of a recessed part index | exponent is small.

(E) Measurement of zeta potential of polishing liquid composition Measurement was performed under the following conditions using "Zeta Probe" manufactured by Agilent Technologies.
・ Measurement temperature: 25 ± 2 ℃
・ Measurement sample: Polishing liquid composition ・ Density Ratio: 7.13 g / ml

2. Evaluation of polishing composition (Examples 1 to 11, Comparative Examples 1 to 6) [Creation of test pieces]
From a silicon oxide film (oxide film) having a thickness of 2000 nm formed on one side of a silicon wafer by TEOS-plasma CVD method, a 40 mm × 40 mm square piece was cut out to obtain an oxide film test piece.

[Measurement of polishing rate of silicon oxide film (film to be polished)]
As a polishing apparatus, “MA-300” manufactured by Musashino Electronics Co., Ltd. having a surface plate diameter of 300 mm was used. As the polishing pad, a hard urethane pad “IC-1000 / Sub400” manufactured by Nitta Haas was used. The polishing pad was attached to the surface plate of the polishing apparatus. The test piece was set in a holder, and the holder was placed on the polishing pad so that the surface of the test piece on which the silicon oxide film was formed faced down (so that the oxide film faces the polishing pad). Further, a weight was placed on the holder so that the load applied to the test piece was 300 g weight / cm ² . While dropping the polishing composition at a rate of 50 mL / min on the center of the surface plate to which the polishing pad is attached, each of the surface plate and the holder is rotated in the same rotational direction at 90 r / min for 1 minute to form an oxide film. The specimen was polished. After polishing, the substrate was washed with ultrapure water and dried, and the oxide film test piece was used as a measurement object by an optical interference type film thickness measuring device described later.

Before and after polishing, the thickness of the oxide film was measured using an optical interference type film thickness measuring device (“Lambda Ace VM-1000” manufactured by Dainippon Screen). The polishing rate of the oxide film was calculated by the following formula and is shown in Table 1 below.
Polishing rate of oxide film (nm / min)
= [Oxide film thickness before polishing (nm)-Oxide film thickness after polishing (nm)] / Polishing time (min)

[Measurement of polishing rate of silicon nitride film (oxidation stopper film)]
Except for using a silicon nitride film test piece instead of the silicon oxide film test piece as the test piece, the polishing of the silicon nitride film (nitride film), the film thickness Measurement and polishing rate were calculated. The polishing rate of the nitride film is shown in Table 1 below.

[Polishing speed ratio]
The ratio of the polishing rate of the silicon oxide film to the polishing rate of the silicon nitride film was defined as the polishing rate ratio, and was calculated by the following formula and shown in Table 1 below. It shows that polishing selectivity is so high that the value of polishing rate ratio is large.
Polishing rate ratio = polishing rate of silicon oxide film (nm / min) / polishing rate of silicon nitride film (nm / min)

[Evaluation method of residual abrasive grain amount]
The oxide film test piece after polishing was used as a measurement sample, and measurement was performed under the following conditions using a micro fluorescent X-ray analyzer (“XGT-5000” manufactured by HORIBA).
Measurement time: 60 seconds XGT diameter: 100 um
Pulse processing time: P3
X-ray tube voltage: 30 kV
Tube current: 0.22 mA
The fluorescent X-ray intensity (unit: cps) of the obtained Ce was defined as the amount of residual abrasive grains.

As shown in Table 1, Examples 1 to 11 in which the concave index of the particle A is 1.000 or more and 1.035 or less and the zeta potential of the polishing composition is −90 mV or more and less than 0 mV have a positive zeta potential. Compared with Comparative Examples 1 and 2 and Comparative Example 3 with a zeta potential of less than −90 mV and Comparative Examples 4 to 5 with a recess index exceeding 1.035, the polishing selectivity is improved while improving the polishing selectivity. did it. Further, in Examples 1 to 11 containing the particle A having a recess index of 1.000 or more and 1.035 or less and a predetermined amount of the compound B, the content of the compound B is 6.0 × 10 ⁻⁵ g / m ^2. Comparative Examples 1 and 2 that are less than 1, Comparative Example 3 in which the content of Compound B exceeds 3.8 × 10 ⁻¹ g / m ² , Comparative Examples 4 to 5 in which the recess index exceeds 1.035, Compound B (anion) As compared with Comparative Example 6 containing polydimethyldiallylammonium chloride (cationic compound) instead of the active compound), the polishing selectivity was improved while ensuring the polishing rate.

  As described above, the polishing composition according to the present disclosure is useful in a method for manufacturing a semiconductor substrate for high density or high integration.

Claims (12)

A polishing liquid composition comprising polyhedral cerium oxide particles A, water, and a compound B having an anionic group ,
The zeta potential is −90 mV or more and less than 0 mV,
The mass ratio B / A between the cerium oxide particles A and the compound B having an anionic group is 0.2 or more and 1.6 or less,
The concave index of the cerium oxide particles A is 1.000 or more and 1.035 or less,
The concave portion index is a polishing liquid composition that is an average value of the ratio (S / L) of the peripheral length S of the particle A to the envelope peripheral length L. The content of the compound B is 3.8 × 10 ^-1 g / m ² or less 6.0 × 10 ^-5 g / m ² or more of the surface area of the cerium oxide particles A, according to claim 1 Polishing liquid composition. A polishing liquid composition comprising at least polyhedral cerium oxide particles A, water, and a compound B having an anionic group,
The concave index of the cerium oxide particles A is 1.000 or more and 1.035 or less,
The content of the compound B is 5.1 × 10 ⁻⁴ g / m ² or more and 3.8 × 10 ⁻¹ g / m ² or less with respect to the surface area of the cerium oxide particles A,
The concave portion index is a polishing liquid composition that is an average value of the ratio (S / L) of the peripheral length S of the particle A to the envelope peripheral length L. The polishing composition according to any one of claims 1 to 3 , wherein the compound B is at least one selected from a polyacrylic acid ammonium salt, a polymethacrylic acid ammonium salt, and a polystyrene sulfonic acid ammonium salt. The polishing composition according to any one of claims 1 to 4 , wherein the pH is 2.5 or more and 8.5 or less. The polishing liquid composition according to any one of claims 1 to 5, wherein an average primary particle diameter of the cerium oxide particles A is 15 nm or more and 300 nm or less.   A method for producing a semiconductor substrate, comprising a step of polishing a substrate to be polished using the polishing composition according to claim 1.   A method for polishing a substrate, comprising a step of polishing a substrate to be polished using the polishing composition according to claim 1, wherein the substrate to be polished is a substrate used for production of a semiconductor substrate. A slurry containing polyhedral cerium oxide particles A and water,
The average primary particle diameter of the cerium oxide particles A is 15 nm or more and 300 nm or less,
The concave index of the cerium oxide particles A is 1.000 or more and 1.035,
The said recessed index is a cerium oxide slurry used for manufacture of polishing liquid composition which is an average value of ratio (S / L) of perimeter length S of this particle A, and envelope perimeter length L.   The slurry of Claim 9 which further contains the compound B which has an anionic group. A kit for producing the polishing composition according to any one of claims 1 to 6 ,
A dispersion containing polyhedral cerium oxide particles A includes a container-containing particle A dispersion stored in a container,
The concave index of the cerium oxide particles A is 1.000 or more and 1.035 or less,
The concave index is an average value of the ratio (S / L) of the peripheral length S of the particle A to the envelope peripheral length L.
Polishing fluid kit.   The polishing liquid kit according to claim 11, further comprising a compound B having an anionic group housed in a container different from the container-containing particle A dispersion.