TW201712100A - Slurry and substrate polishing method using same - Google Patents

Abstract

The present disclosure relates to a slurry and a substrate polishing method using the same, and more particularly, to a slurry that can be used to planarize an oxide by a chemical mechanical polishing process in a semiconductor manufacturing process, and a substrate polishing method using the same. A slurry according to an embodiment of the present invention is an oxide-polishing slurry, and includes: a first slurry containing a polishing abrasive and a first polishing inhibitor for inhibiting polishing of a first material different from the oxide; and a second slurry containing a polishing accelerator for accelerating polishing of the oxide. The first slurry may contain a dispersant for dispersing the abrasive and may further contain a dispersion stabilizer for maintaining uniform dispersion of the abrasive. The second slurry may contain a second polishing inhibitor for inhibiting polishing of a second material different from the oxide. The slurry and the substrate polishing method of the present invention are capable of maintaining polishing selectivity between an oxide and materials other than the oxide in an optimum range by adjusting the polishing rates thereof.

Description

Slurry and substrate polishing method using same

The present invention relates to a slurry; and a substrate polishing method using the same, and more particularly to a slurry capable of efficiently performing oxide polishing by means of a chemical mechanical polishing process in a semiconductor manufacturing process; and a use thereof Substrate polishing method.

As the size of the semiconductor device shrinks and the number of metal wiring layers increases, the surface irregularity of each layer shifts to the next layer, and therefore, the roughness of the bottom layer becomes important. This roughness may have a significant impact on the next step, making it difficult to perform the lithography process. Therefore, in order to improve the yield of the semiconductor device, a planarization process is basically used to reduce the roughness of the irregular surface generated in many process steps. The planarization is achieved by various methods such as a reflow method performed after forming a thin film, an etch back method performed after forming a thin film, and a chemical mechanical polishing (CMP) method.

The CMP process grinds the surface of a semiconductor wafer by supplying a slurry containing the abrasive and various compounds while the surface is in contact with the polishing pad in a rotational motion. In other words, the CMP process means a process in which the surface of the substrate or its upper layer is chemically and mechanically ground and planarized using a slurry and a polishing pad.

For example, in order to form a device insulating layer in a conventional process for fabricating a flash memory device, a CMP process for ruthenium oxide film is used, and a polysilicon film is used as the polishing stop layer. In other words, after the gate insulating film and the polysilicon film are formed on the substrate, the trench is formed by etching the substrate to a predetermined depth using the nitride film on the polysilicon film as a hard mask. Subsequently, a hafnium oxide film is formed to cover the trench, and then the device insulating layer is formed by grinding the hafnium oxide film until the polysilicon film is exposed.

Therefore, in order to form a trench in a plurality of heterogeneous material layers and to form a hafnium oxide film in the trench, a slurry having a high oxide polishing rate and having an optimum polishing selectivity to simultaneously suppress the polishing of the nitride film and the polysilicon film is required. material. However, various studies have been conducted so far only to improve the grinding selectivity for oxides, and it has not been developed to adjust the optimum grinding options for nitride films and polysilicon films by reducing the oxide polishing rate to a lower rate. Sexual oxide grinding slurry.

On the other hand, Korean Patent Publication No. 10-2009-0003985 discloses a slurry for grinding tantalum nitride which suppresses the grinding of a tantalum nitride film to improve the polishing selectivity to an oxide. Even in this case, the polishing selectivity of the oxide with respect to the nitride may be improved, but the same problem as described above still exists.

[Related Technical Documents] [Patent Documents] Korean Patent Publication No. 10-2009-0003985

The present invention provides an oxide polishing slurry and a substrate polishing method using the same.

The present invention provides a slurry substrate polishing method capable of maintaining the polishing selectivity between the oxide and a material not the oxide in an optimum range by adjusting the polishing rate of the oxide.

A slurry according to an embodiment of the present invention is an oxide polishing slurry, and comprises: a first slurry containing a grinding abrasive, a dispersing agent for dispersing the abrasive, and a method for suppressing different from the oxide a ground first abrasive inhibitor of the first material; and a second slurry containing a polishing accelerator for promoting the grinding of the oxide.

The second slurry may contain a ground second inhibiting agent for inhibiting grinding of a second material different from the oxide and the first material.

The first slurry and the second slurry may be mixed at a ratio of 1:0.5 to 1:1.5.

The abrasive may comprise cerium oxide (ceria) particles and may be included in an amount from 0.1% to 10% by weight relative to the total weight of the first slurry.

The grinding selectivity between the oxide and the first material may range from 100:1 to 300:1, and the grinding selectivity between the oxide and the second material may be 20:1 In the range of 60:1.

The content of the first grinding inhibitor may be less than the content of the polishing accelerator.

The content of the first grinding inhibitor may be less than the content of the second grinding inhibitor.

The first grinding inhibitor may be included in an amount of 0.002% by weight to 0.02% by weight relative to the total weight of the first slurry.

The grinding accelerator may be included in an amount of 0.1% by weight to 1.355% by weight based on the total weight of the second slurry.

The second grinding inhibitor may be included in an amount of from 0.15% by weight to 1% by weight relative to the total weight of the second slurry.

The first polishing inhibitor may comprise a non-ionic material having both a hydrophobic group and a hydrophilic group.

The first polishing inhibitor may comprise at least one of the following: a polypropylene glycol-b-polyethylene glycol-b-polypropylene glycol (PEP) copolymer (polypropylene glycol-b-polyethyleneglycol-b-polypropyleneglycol (PEP) copolymer), Polysorbates, octoxynol, polyethylene glycol, octadecyl ether, nonylphenol ethoxylate, ethylene oxide ), glycolic acid or glycerol ethoxylate.

The grinding accelerator may comprise a monomolecular material in the family of alkanolamines having a hydroxyl group and an amine group.

The polishing accelerator may comprise at least one of the following: aminomethyl propanol (AMP), ethanolamine, heptaminol, isoetharine, methanolamine , diethylethanolamine or N-methylethanolamine.

The second grinding inhibitor may comprise an anionic material having a carboxyl group.

The second grinding inhibitor may comprise at least one of poly(acrylic acid) (PAA), poly(alkyl methacrylate), acrylamide, methacrylamide or ethyl - Methacrylamide.

A method for polishing a substrate according to an embodiment of the present invention includes the steps of: preparing a substrate having an oxide layer and a heterogeneous material layer composed of a plurality of heterogeneous materials not being the oxide; preparing a first slurry The first slurry contains an abrasive, a dispersant for dispersing the abrasive, and a first grinding inhibitor for inhibiting grinding of the first material among the plurality of heterogeneous materials; preparing a second slurry, The second slurry contains a polishing accelerator for promoting the grinding of the oxide and a second polishing inhibitor for inhibiting the grinding of the second material among the plurality of heterogeneous materials; and the first slurry is used The oxide layer is ground while the second slurry is supplied onto the substrate.

The preparing of the substrate may include the steps of: forming a first material layer composed of the first material on the substrate; and forming a second material composed of the second material on the first material layer a material layer; forming a trench in the first material layer and the second material layer; and forming an oxide layer on an entire surface including the trench.

In the grinding of the oxide layer, the polishing rate of the oxide layer may be faster than the polishing rate of the second material, and the polishing rate of the second material may be faster than the first The rate of grinding of the material.

In the grinding of the oxide layer, a grinding selectivity between the oxide and the first material may be maintained in a range of 100:1 to 300:1, and the oxide and the first The grinding selectivity between the two materials can be maintained in the range of 20:1 to 60:1.

In the grinding of the oxide layer, the first slurry and the second slurry may be supplied onto the substrate at a mixing ratio of 1:0.5 to 1:1.5.

According to the present invention, a slurry and a substrate polishing method using the same provide a technical feature in which a slurry obtained by mixing a first slurry containing a first polishing inhibitor and a second slurry containing a polishing accelerator is used. It is possible to achieve a high polishing rate for oxide (SiO ₂ ), and it is possible to adjust the polishing rate of an oxide-free material such as polysilicon or nitride (Si ₃ N ₄ ) to an optimum range.

Hereinafter, specific embodiments will be described in more detail with reference to the accompanying drawings. However, the invention may be embodied in different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete. In the description, the same elements are denoted by the same reference numerals. In the drawings, the dimensions of layers and regions are exaggerated for clarity of illustration. Like reference numerals refer to like elements throughout.

A slurry according to an embodiment of the present invention is an oxide abrasive slurry, and comprises: a first slurry containing a abrasive abrasive and a first polishing inhibitor for inhibiting grinding of a first material different from the oxide; And a second slurry containing a polishing accelerator for promoting the polishing of the oxide. The first slurry may contain a dispersant for dispersing the abrasive, and may further contain a dispersion stabilizer for maintaining uniform dispersion of the abrasive. The second slurry may contain a second polishing inhibitor for inhibiting the grinding of a second material different from the oxide.

The abrasive, dispersant, dispersion stabilizer, and first grinding inhibitor contained in the first slurry may be contained in the first solution. For example, the abrasive, dispersant, dispersion stabilizer, and first milling inhibitor are dispersed and dispersed in water, especially deionized water. Further, the first pH adjusting agent may be further contained in the first slurry to adjust the pH of the first slurry. Such a first slurry is in the form of a liquid in which the abrasive is dispersed, and the content of each component is appropriately adjusted.

Further, the polishing accelerator and the second polishing inhibitor contained in the second slurry may be contained in the second solution. In other words, the grinding promoter and the second grinding inhibitor are dispersed in water, especially deionized water, and the second pH adjusting agent can be further contained in the second slurry to adjust the pH of the second slurry.

The first slurry and the second slurry are mixed with a diluent, and the mixed slurry is supplied as an oxide polishing slurry to the surface of the grinding target, and the diluent may be water, especially deionized water. Although the abrasive, the dispersant, the dispersion stabilizer, and the first polishing inhibitor contained in the first slurry, and the polishing accelerator and the second polishing inhibitor contained in the second slurry may be prepared as a single slurry, a first slurry containing an abrasive, a dispersant, a dispersion stabilizer, and a first grinding inhibitor, and a second slurry containing a polishing accelerator and a second grinding inhibitor may be separately prepared so that the first slurry and the second slurry The slurry is mixed with the diluent before grinding, and the mixed slurry is supplied to the grinding target. This is because, when the first slurry and the second slurry are repeatedly used in the polishing process without being separated for a long period of time, the dispersion stability and effective life of the slurry may be due to the second slurry. The ionic characteristics of the polishing accelerator and the second polishing inhibitor are reduced.

The abrasive may be at least one metal oxide selected from the group consisting of cerium oxide (SiO ₂ ), cerium oxide (CeO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), Zirconia (ZrO ₂ ) and yttrium oxide (GeO ₂ ). The abrasive may comprise ceria (CeO ₂ ) having a high grinding selectivity to the oxide.

Further, the abrasive may be included in an amount of 0.1% by weight to 10% by weight based on 100% by weight of the first slurry. When the content of the abrasive is less than 0.1% by weight, the abrasive effect is negligible. On the other hand, when the content of the abrasive is more than 10% by weight, the polishing rate becomes too high, and therefore, the target film may be excessively ground and scratches may be formed.

The crystal structure of the abrasive particles constituting the abrasive can be analyzed by XRD measurement, and the abrasive particles have a crystal structure such as wet ceria and have a polyhedral crystal face.

The average particle size of the abrasive particles can range from 5 nm to 100 nm. When the average particle size of the abrasive particles is less than 5 nm, the abrasive target film cannot be sufficiently ground, and thus the polishing rate is low. On the other hand, when the average particle size of the abrasive particles is larger than 100 nm, minute scratches are formed on the polishing target film. The average particle size of the abrasive particles may be from 20 nm to 80 nm because in such a range, minute scratches are not formed on the polishing stop layer, and the polishing rate of the polishing target film is not lowered.

The dispersant serves to prevent agglomeration between the abrasive particles by uniformly dispersing the abrasive in the first slurry, and a cationic polymer material, an anionic low molecular weight material, an acid containing a hydroxyl group or an acid containing an amino group can be used. In addition, the dispersant can adjust the zeta potential of the abrasive. In other words, the cationic dispersant can increase the zeta potential of the abrasive to a positive potential, and the anionic dispersant can reduce the zeta potential of the abrasive to a negative potential. Therefore, depending on the dispersant contained in the slurry, the zeta potential of the abrasive can be maintained as it is or can be finely adjusted toward a positive potential or a negative potential.

The cationic polymeric dispersant may comprise at least one selected from the group consisting of polylysine, polyethyleneimine, benzethonium chloride, cetrimonium bromide, cetrimonium chloride, tetramethylammonium hydroxide. , distearyl dimethyl ammonium chloride, polydimethylamine-co-epichlorohydrin and polyallylamine.

The anionic low molecular weight dispersant may comprise at least one selected from the group consisting of oxalic acid, citric acid, polysulfuric acid, polyacrylic acid, polymethacrylic acid (Darvan CN), and materials containing at least one of its salts, or may comprise Its copolymer acid.

The acid containing a hydroxyl group may comprise at least one selected from the group consisting of hydroxybenzoic acid, ascorbic acid, and a material containing at least one salt thereof, and the acid containing an amino group may include at least one selected from the group consisting of the following: Pyridinecarboxylic acid, glutamic acid, tryptophan, aminobutyric acid and materials containing at least one of its salts.

The dispersant may be included in the range of 0.01% by weight to 1% by weight based on the total weight of the first slurry. When the content of the dispersant is less than 0.01% by weight, it is difficult to disperse and precipitation may occur. On the other hand, when the content of the dispersant is more than 1% by weight, the dispersion stability of the slurry may be lowered due to aggregation of the polymer material and high ionization density. The dispersant may be included in the range of 0.05% by weight to 0.3% by weight based on the total weight of the slurry, because in such a range, it is more advantageous that the dispersion is highly stable and finely adjusts the zeta potential of the abrasive.

The dispersion stabilizer acts as a pH buffer in the slurry, thereby suppressing chemical changes in the first slurry caused by external factors, in order to prevent coalescence between the abrasive particles and uniformly disperse the abrasive particles, and thus to suppress The formation of scratches. The dispersion stabilizer may comprise an organic acid. In this case, the pKa value which is the absolute value of the dissociation constant is in the range of 9 to 12, and the dispersion stabilizer may contain an α-amino acid in which the carboxyl group (COOH) and the amine group (NH ₂ ) are bonded to the same among the amino acids. Carbon (C) atom. The α-amino acid can be classified into a neutral amino acid, an acidic amino acid, and a basic amino acid depending on the number of carboxyl groups (COOH) and amine groups (NH ₂ ). The neutral amino acid may comprise at least one selected from the group consisting of alanine, glycine, tyrosine, and valine having an equal number of amine groups and carboxyl groups. The acidic amino acid may comprise at least one selected from the group consisting of aspartic acid, glutamic acid, and citric acid, wherein the number of carboxyl groups is greater than the number of amine groups. The basic amino acid may comprise lysine, wherein the number of amine groups is greater than the number of carboxyl groups.

The dispersion stabilizer may be included in the range of 0.001% by weight to 0.1% by weight based on the total weight of the first slurry based on 5% by weight of the abrasive contained in the first slurry. When the content of the dispersion stabilizer is less than 0.001% by weight, the dispersion stabilizer has a low pH buffering ability, and the effect of the dispersion stabilizer is therefore insufficient. On the other hand, when the content of the dispersion stabilizer is more than 0.1% by weight, the dispersion stability of the abrasive is lowered and precipitation may occur. The dispersion stabilizer may be included in the range of 0.005 wt% to 0.05 wt% with respect to the total weight of the slurry, because within such a range, pH buffering ability is excellent and dispersion stability is more advantageous.

The first abrasive inhibitor inhibits the grinding of materials that are not the target of the grinding. In other words, the first abrasive inhibitor inhibits the grinding of each material to adjust the milling selectivity. Materials that are not intended for grinding may contain a variety of heterogeneous materials having different compositions. For example, when the oxide is ground, the first polishing inhibitor can adjust the selectivity by inhibiting the grinding of the first material and the second material contained in the plurality of heterogeneous materials, respectively.

Such a first polishing inhibitor is a material having a high bonding strength to a first material (for example, polycrystalline germanium) as compared with an oxide, and a nonionic material having both a hydrophobic group and a hydrophilic group can be used. Such a first abrasive inhibitor has both hydrophobic and hydrophilic properties and is thus adsorbed on the surface of the hydrophobic polycrystalline germanium film to form a passivation film. Thus, the first milling inhibitor reduces the polishing rate of the polysilicon at a relatively high rate to adjust the milling selectivity.

Various non-ionic materials can be used as the first grinding inhibitor. For example, the first grinding inhibitor may comprise at least one of the following: polypropylene glycol-b-polyethylene glycol-b-polypropylene glycol (PEP) copolymer, polysorbate, octylphenol, polyethylene Alcohol, stearyl ether, nonylphenol ethoxylate, ethylene oxide, glycolic acid or glycerol ethoxylate.

The content of the first grinding inhibitor may be from about 0.002% by weight to 0.02% by weight relative to the total weight of the first slurry. When the content of the first grinding inhibitor is less than 0.002% by weight, for example, the polishing rate of the polycrystalline silicon film used as the polishing stopper layer is too high. On the other hand, when the content of the first polishing inhibitor is more than 0.02% by weight, an excessive amount of the first polishing inhibitor is adsorbed on the polycrystalline germanium film, and the polishing selectivity between the oxide film and the polycrystalline germanium film cannot be maintained within an appropriate range. . Further, when the content of the first grinding inhibitor is in the range of 0.005 wt% to 0.015 wt%, the selectivity adjustment effect can be sufficiently obtained, and the polishing rate of the polysilicon film can be maintained at an appropriate level.

A grinding accelerator is included in the second slurry to promote grinding of the abrasive target material. In other words, the polishing accelerator promotes the grinding of the grinding target material and suppresses the grinding of the material that is not the grinding target, thus adjusting the grinding selectivity. For example, when the oxide is ground, the polishing accelerator promotes the grinding of the oxide and inhibits the grinding of the polycrystalline germanium and nitride which are not oxides, respectively, to adjust the selectivity.

A monomolecular material in the alkanolamine family having both a hydroxyl group (OH) and an amine group (NH ₂ ) can be used as such a polishing accelerator. The pKa value (absolute value of the dissociation constant) of such a polishing accelerator is about 9.7, and thus dissociates into positively charged NH ₃ ⁺ , which is positively charged in a solution having a pH of less than or equal to 9.7. The dissociated NH ₃ ⁺ interacts with, for example, a negatively charged oxide film (SiOH ⁻ ) in solution to promote the reaction of the oxide film in the form of Si(OH) ₄ , and thus increase the polishing rate of the oxide film.

Single molecule materials in the alkanolamine family can be used as grinding accelerators. For example, the polishing accelerator may comprise at least one of the following: aminomethylpropanol (AMP), ethanolamine, methanide, iso-allin, methanolamine, diethylethanolamine or N-methylethanolamine. Such a monomolecular material may have a hydroxyl group and an amine group as a functional group.

The polishing accelerator may be included in an amount of from about 0.1% by weight to about 1.35 % by weight based on the total weight of the second slurry. When the content of the polishing accelerator is less than 0.1% by weight, the polishing rate of the polishing target (such as an oxide film) is too low, or the polishing rate of a material (such as a nitride film) which is not an abrasive target is too high, and an oxide cannot be obtained. An appropriate level of polishing selectivity between the film and the nitride film. On the other hand, when the content of the polishing accelerator is more than 1.35 wt%, the polishing rate of the nitride film is remarkably lowered and the polishing efficiency may be lowered accordingly. Further, when the content of the polishing accelerator is in the range of 0.5% by weight to 1% by weight, the polishing rate of the oxide film and the nitride film can be adjusted to an optimum level.

A second grinding inhibitor is included in the second slurry to inhibit grinding of the material that is not the target of the grinding. In other words, the second grinding inhibitor inhibits the grinding of each material to adjust the milling selectivity. For example, when the oxide is ground, the second polishing inhibitor can adjust the selectivity by inhibiting the grinding of the first material and the second material contained in the plurality of foreign materials, respectively.

An anionic material having at least one carboxyl group can be used as the second grinding inhibitor. Such polishing inhibitor of the second pKa value (the absolute value of the dissociation constant of the solution) is about 4, and thus dissociated into negatively charged COO ^-, which is a solution pH of at least 4 negatively charged. Dissociation COO ^- groups may be adsorbed on the abrasive material is not the target, for example adsorbed on a positively charged nitride.

An anionic material having a carboxyl group can be used as the second grinding inhibitor. For example, the second grinding inhibitor may comprise at least one of poly(acrylic acid) (PAA), poly(alkyl methacrylate), acrylamide, methacrylamide or ethyl-methacryl Guanamine. Each anionic material contains at least one carboxyl group and may have only a carboxyl group or may further have other functional groups than the carboxyl group.

The content of the second grinding inhibitor may be from about 0.15% by weight to about 1% by weight relative to the total weight of the second slurry. When the content of the second grinding inhibitor is less than 0.15% by weight, the second grinding inhibitor is not sufficiently adsorbed on the nitride film, and the selective adjustment effect cannot be sufficiently obtained. On the other hand, when the content of the second grinding inhibitor is more than 1% by weight, an excessive amount of the second grinding inhibitor is adsorbed on the nitride film, and the polishing rate of the nitride film is thus excessively lowered. Therefore, the grinding selectivity between the oxide and the second material (such as nitride) may be outside the target range of 20:1 to 60:1.

The first pH adjuster and the second pH adjuster are contained in the first slurry and the second slurry, respectively, to adjust the pH of each slurry. These pH adjusters may contain nitric acid, ammonia water, and the like. In one embodiment of the invention, the pH of the first slurry and the second slurry can be adjusted equally to the range of 4 to 8 using these pH adjusting agents. When the pH is less than 4, the dispersion stability may be lowered. On the other hand, when the pH is more than 8, the polishing rate of a material which is not an abrasive target (such as a polycrystalline ruthenium film used as a polishing stopper layer) may be significantly increased due to strong alkalinity. The pH of the first slurry and the second slurry can be adjusted to a range of 6 to 7, because within such a range, dispersion stability can be maintained, and the polishing target material and the non-abrasive target material can be optimally maintained. The selectivity of the grinding between the materials.

The first slurry and the second slurry may be mixed at a ratio of 1:0.5 to 1:1.5, and in this case, the first slurry and the diluent may be mixed at a ratio of 1:3 to 1:8. When the first slurry and the second slurry are mixed at a ratio of 1:0.5 to 1:1.5 and the first slurry and the diluent are mixed at a ratio of 1:3 to 1:8 to prepare an oxide slurry, it is possible Maintain the oxide polishing rate in the range of 2000 Å/min to 2500 Å/min and maintain the nitride polishing rate in the range of 50 Å/min to 150 Å/min, preferably 50 Å/min to 100 Å/min. Inside. Furthermore, in this case, the polishing rate of the polysilicon is maintained at 50 Å/min or less, preferably 20 Å/min or less, and it is therefore possible to combine the oxide with the first material (eg Grinding selectivity between polycrystalline germanium) is maintained in the range of 100:1 to 300:1 and the grinding selectivity between the oxide and the second material (eg nitride) is maintained in the range of 20:1 to 60:1 .

The slurry was prepared according to the above examples and applied to a semiconductor substrate to evaluate the polishing characteristics of the slurry. The results will be described below.

[Experimental example]

The process used to prepare the slurry is not significantly different from the typical process used to prepare the slurry and will be briefly described.

First, in order to prepare a first slurry, a container for preparing a first slurry is prepared, and a desired amount of deionized water, an anionic dispersant, and an organic acid (as a dispersion stabilizer) are placed in a container and thoroughly mixed. Then, a predetermined amount of wet cerium oxide particles having a polyhedral crystal face and a predetermined average abrasive grain size are placed as an abrasive into the container and uniformly mixed therein. A predetermined amount of a polypropylene glycol-b-polyethylene glycol-b-polypropylene glycol (PEP) copolymer was placed as a first grinding inhibitor into the container and uniformly mixed therein. Subsequently, a pH adjusting agent such as nitric acid is placed in the container to adjust the pH of the first slurry.

To prepare the second slurry, a container for preparing the second slurry is prepared, and a predetermined amount of deionized water, a grinding accelerator, and a second grinding inhibitor are placed in the container and thoroughly mixed. Aminomethylpropanol (AMP) is used as a grinding accelerator, and poly(acrylic acid) (PAA) is used as a second grinding inhibitor. Subsequently, a pH adjusting agent such as nitric acid is placed in the container to adjust the pH of the second slurry.

Subsequently, the desired amount of deionized water (as a diluent), the first slurry, and the second slurry are mixed in a vessel to prepare an oxide slurry. The order in which each material is added and mixed is not particularly limited.

In this experimental example, the cerium oxide (cerium oxide) particles were added to 5% by weight with respect to the total weight of the first slurry, and the dispersing agent and the dispersion stabilizer were added to 0.15 with respect to the total weight of the first slurry, respectively. % by weight and 0.02% by weight. Further, the first grinding inhibitor is added in various amounts of 0% by weight to 0.02% by weight with respect to the total weight of the first slurry, and the grinding accelerator and the second grinding inhibitor are respectively based on the total weight of the second slurry Various amounts are added from 0% by weight to 1.35% by weight and from 0% by weight to 0.3% by weight.

In other words, the plurality of first slurry and second slurry are prepared according to the added amounts of the first grinding inhibitor, the grinding accelerator, and the second grinding inhibitor contained in the first slurry and the second slurry. Nitric acid was used to adjust the respective pH values of the first slurry and the second slurry to 6.5. The first slurry and the second slurry may contain unavoidable impurities and pure water which are not the aforementioned components. The resulting first and second slurries were mixed in deionized water and the first slurry, the second slurry, and deionized water were mixed at a ratio of 0.7:0.8:3.5 to prepare an oxide slurry.

Figure 1 shows the results of milling using a slurry of various amounts of a first milling inhibitor added in accordance with an embodiment of the present invention. Figure 2 is a graph showing the rate of oxide polishing relative to the concentration of the first milling inhibitor. Figure 3 shows the results of milling using a slurry of various amounts of grinding accelerator added in accordance with an embodiment of the present invention. Figure 4 is a graph showing the oxide polishing rate relative to the concentration of the polishing accelerator. Figure 5 shows the results of milling using a slurry in which various amounts of a second grinding inhibitor are added in accordance with an embodiment of the present invention. Figure 6 is a graph showing the oxide polishing rate relative to the concentration of the second polishing inhibitor. Here, the polishing rates of yttrium oxide, tantalum nitride, and polysilicon are obtained by grinding a yttria-coated wafer, a tantalum nitride-coated wafer, and a polycrystalline silicon-coated wafer, respectively. The grinding selectivity means the ratio between the polishing rate of the yttrium oxide film and the polishing rate of the tantalum nitride film or the polysilicon film. In other words, the grinding selectivity is the value of the polishing rate of the yttrium oxide film divided by the polishing rate of the tantalum nitride film or the polysilicon film.

As can be seen in Figures 1 and 2, the polishing rates of yttrium oxide, tantalum nitride, and polycrystalline germanium generally decrease as the amount of the first polishing inhibitor increases. In addition, it was found that the polishing rate of cerium oxide was faster than the polishing rate of cerium nitride, and the polishing rate of cerium nitride was adjusted faster than the polishing rate of polycrystalline germanium. The first milling inhibitor significantly reduces the polishing rate of the polycrystalline germanium. The principles involved have been described.

When the content of the first grinding inhibitor contained in the first slurry is 0.002% by weight and the contents of the grinding accelerator and the second grinding inhibitor contained in the second slurry are 0.9% by weight and 0.2% by weight, respectively The grinding selectivity between cerium oxide and polycrystalline germanium is about 236, which is an extremely high value compared to the grinding selectivity 46 when the content of the first grinding inhibitor is 0% by weight.

In addition, as can be seen in FIGS. 3 and 4, as the amount of the polishing accelerator increases, the polishing rate of tantalum nitride and polycrystalline germanium is slightly lowered, but the polishing rate of cerium oxide is remarkably increased. The principles involved have been described. When the content of the first grinding inhibitor contained in the first slurry is 0.01% by weight and the contents of the grinding accelerator and the second grinding inhibitor contained in the second slurry are 0.1% by weight and 0.2% by weight, respectively The grinding selectivity between cerium oxide and tantalum nitride is 25 and the grinding selectivity between cerium oxide and polycrystalline germanium is 153. These values are compared with the grinding selectivity 13 between cerium oxide and tantalum nitride when the content of the grinding accelerator is 0% by weight and the cerium oxide and polycrystalline silicon when the content of the polishing accelerator is 0% by weight. Selectivity 92 is a very high value.

In addition, as can be seen in FIGS. 5 and 6, the polishing rates of yttrium oxide, tantalum nitride, and polycrystalline germanium generally decrease as the amount of the second polishing inhibitor increases. It was found that the second grinding inhibitor significantly reduced the polishing rate of cerium oxide and cerium nitride, and the polishing rate of cerium nitride was the highest. The principles involved have been described.

In other words, when the content of the first grinding inhibitor contained in the first slurry is 0.01% by weight and the content of the grinding accelerator and the second grinding inhibitor contained in the second slurry is 0.9% by weight and At 0.15% by weight, the polishing selectivity between cerium oxide and cerium nitride is about 30, which is an extremely high value compared to the polishing selectivity 5 when the content of the second polishing inhibitor is 0% by weight.

Figure 7 is a graph used to compare the rate of oxide polishing relative to the type of first milling inhibitor in another experiment. Figure 8 shows the results of oxide milling relative to the type of first milling inhibitor.

As can be seen in Figures 7 and 8, it was found that when having a conventional grinding inhibitor polyvinylpyrrolidone (hereinafter referred to as PVP) for polycrystalline germanium, when having both a hydrophobic group and a hydrophilic group and having a polycrystalline germanium A high bonding strength nonionic material polypropylene glycol-b-polyethylene glycol-b-polypropylene glycol (PEP) copolymer (hereinafter referred to as PEP) is used as the first grinding inhibitor, and the polishing rate of cerium oxide is The reduction rate is reduced from -9.4 to -6.7, and the rate of decrease in the polishing rate of the polysilicon is further reduced.

The reason why the reduction rate of the polishing rate of cerium oxide is reduced when PEP is used as the first grinding inhibitor compared to when using the conventional PVP can be seen from FIGS. 9 and 10. Figure 9 shows the surface potential (i.e., zeta potential) values of cerium oxide particles in the corresponding case where PVP and PEP are added to the cerium oxide particles. Fig. 10 is a graph for comparing changes in zeta potential.

As can be seen in Figures 9 and 10, the surface potential of the cerium oxide particles in the slurry is in the range of -45 mV to -50 mV and increases when nonionic PEP or PVP is added to the slurry. When the rate of increase of the surface potential with respect to the concentration is examined, the rate of increase of the surface potential is about 127 in the case of PVP and 28 in the case of PEP. Therefore, the increase rate of the surface potential is larger in the case of PVP than in the case of PEP. When the oxide is ground, the surface potential of the oxide is in the range of -50 mV to -60 mV. Therefore, the electrostatic force between the oxide and the cerium oxide particles (i.e., the electrostatic repulsion force) is smaller in the case of PVP than in the case of PEP, and thus the cerium oxide particles are oxidized as compared with the case of PEP. The adsorption on the object is easier in the case of PVP. Therefore, the rate of decrease in the polishing rate of cerium oxide is attributed to the difference in electrostatic force in the case of PEP to less than in the case of PVP. In addition, it was found that when the first grinding inhibitor contained 0.005% by weight of PEP, the grinding selectivity between cerium oxide and polycrystalline germanium was 160, which was much higher than that of cerium oxide and polycrystalline germanium when the first grinding inhibitor contained an equivalent amount of PVP. The selectivity between grinding is 11.

The conventional grinding inhibitor PVP for polycrystalline germanium significantly reduces the polishing rate of cerium oxide and makes it difficult to find an optimum range of grinding selectivity. On the other hand, when the PEP according to one embodiment of the present invention is used as the first grinding inhibitor, the polishing rate of cerium oxide is moderately lowered, and thus it is easy to adjust the polishing rate of the cerium oxide film. In addition, the grinding selectivity between cerium oxide and polycrystalline germanium is improved, and thus it is possible to adjust the selectivity very high.

The slurry according to one embodiment of the present invention can be used in an oxide polishing process in a semiconductor device fabrication process. For example, in order to form a device insulating layer in a process for fabricating a flash memory device, a pattern can be formed by using a polysilicon film as a polishing stop layer and using a nitride film on the polysilicon film as a hard mask. Therefore, when the yttrium oxide film is formed on a plurality of heterogeneous material layers having such a pattern, the slurry having an appropriate polishing selectivity can be selected depending on the pattern to be polished and the type of the polishing stopper layer used to perform the polishing process. In other words, the following slurry can be used in a semiconductor device manufacturing process which has a high polishing rate for a ruthenium oxide film and an optimum polishing selectivity range in which the polishing rate of the tantalum nitride film is maintained above that of polysilicon The polishing rate of the film is at a certain level in order to reduce the polishing rate of the tantalum nitride and terminate the grinding of the polysilicon film. A semiconductor device manufacturing method using the slurry of the present invention will be described with reference to FIGS. 11A to 11D. The details regarding the slurry described above will be omitted in the following description.

11A through 11D are cross-sectional views for explaining a method of fabricating a semiconductor device in accordance with an embodiment of the present invention. Referring to FIG. 11A, a first material layer 120 and a second material layer 130 are formed on the substrate 110. Various substrates used in the manufacture of the semiconductor device can be used as the substrate 110, and a germanium substrate can be used. The first material layer 120 and the second material layer 130 are formed on the substrate 110. The first material layer 120 may be formed using a material for polishing the termination layer such as polysilicon, and the second material layer 130 may be formed using a material (such as tantalum nitride) for forming a mask layer for patterning. The first material layer 120 and the second material layer 130 may use a physical vapor deposition (PVD) method, a chemical vapor deposition (CVD) method, or a metal organic CVD (MOCVD) method. Formed by an atomic layer deposition (ALD) method or an AL-CVD (CVD-ALD hybrid) method.

Referring to FIG. 11B, after the first material layer 120 is formed on the substrate 110, the pattern 115 is formed by etching the substrate to a predetermined depth using the second material layer 130 as a mask on the first material layer 120. The pattern 115 may be a linear trench for forming a device insulating layer.

As shown in FIG. 11C, an oxide layer 140 is formed on the entire surface of the second material layer 130 including the pattern 115 to cover the pattern 115.

Referring to FIG. 11D, the oxide layer 140 and the second material layer 130 are ground using a slurry having a high polishing rate for the oxide layer 140 film and having an optimum polishing selectivity range, wherein the second material layer 130 The polishing rate is maintained at a level above the polishing rate of the first material layer 120 in order to reduce the polishing rate of the second material layer 130 and terminate the grinding of the first material layer 120. The second material layer 130 may need to be removed during the grinding of the oxide layer 140 in order to improve the characteristics of the device. The slurry maintains the polishing selectivity between the oxide layer 140 and the first material layer 120 in the range of 100:1 to 300:1 and maintains the polishing selectivity between the oxide layer 140 and the second material layer 130. In the range of 20:1 to 60:1.

The grinding process is carried out in a pH range of 4 to 8, and comprises the steps of: grinding the oxide layer 140 using the cerium oxide abrasive particles; generating an NH ₃ ⁺ group by dissociating the amine group of the polishing accelerator; by dissociating the second carboxy polishing inhibitor produced COO ^- groups; and adsorption by hydrophobic groups forming a first passivation film polishing inhibitor. As described above, the generated NH ₃ ⁺ group interacts with the negatively charged ruthenium oxide film (SiOH ⁻ ) in the solution to promote the grinding of the oxide film, and the generated COO ⁻ group inhibits the tantalum nitride film. Grinding. Further, the hydrophobic group of the first polishing inhibitor is adsorbed on the surface of the polysilicon film to form a passivation film, and thus the polishing rate of the polysilicon is suppressed and the polishing rate of the cerium oxide film is moderately lowered. Therefore, it is easy to adjust the polishing rate of the ruthenium oxide film. In addition, the grinding selectivity between cerium oxide and polycrystalline germanium is improved, and thus it is possible to adjust the selectivity very high.

According to an embodiment of the present invention, a high polishing rate for an oxide can be achieved by using a slurry in which a first slurry containing a first polishing inhibitor is mixed with a second slurry containing a polishing accelerator, and The polishing rate of materials that are not oxides, such as polysilicon or nitride, is adjusted to an optimum range. In addition, it is possible to improve the grinding by adjusting the slurry to have high selectivity for each of the different materials that are not oxides and to adjust the grinding selectivity to each of the different materials to produce a certain level of polishing rate difference. stability.

Further, since the first grinding inhibitor moderately reduces the polishing rate of the oxide, it is easy to adjust the polishing rate of the oxide. In addition, the first polishing inhibitor forms a passivation film on the polysilicon film and thus prevents the polysilicon film from being ground, and thus can prevent excessive polishing.

For example, when a substrate is etched to a predetermined depth using a nitride film as a mask on a polysilicon film used as a polishing stop layer in a semiconductor device manufacturing process, it is possible to improve the oxide film with respect to each heterogeneous material layer. Grinding selectivity. Furthermore, by maintaining the polishing selectivity of the oxide film relative to each material layer within an optimum range, it is possible to suppress erosion and dishing and complete the grinding in a single process, and can be attributed to process simplification and cost reduction And improve productivity.

Although the preferred embodiment of the invention has been described and illustrated by the specific embodiments of the present invention, it is intended that the invention may be The embodiments and the terms used in the present invention are subject to various modifications and changes. The modified embodiments are not to be interpreted as independent of the spirit and scope of the invention, but should fall within the scope of the invention.

110‧‧‧Substrate
111‧‧‧ pattern
120‧‧‧First material layer
130‧‧‧Second material layer
140‧‧‧Oxide layer

The illustrative embodiments may be understood in more detail in the following description in conjunction with the accompanying drawings in which: FIG. 1 shows the results of the grinding of a slurry of various amounts of the first grinding inhibitor added using an embodiment in accordance with the present invention. Figure 2 is a graph showing the rate of oxide polishing relative to the concentration of the first milling inhibitor. Figure 3 shows the results of milling using a slurry of various amounts of grinding accelerator added in accordance with an embodiment of the present invention. Figure 4 is a graph showing the oxide polishing rate relative to the concentration of the polishing accelerator. Figure 5 shows the results of milling using a slurry in which various amounts of a second grinding inhibitor are added in accordance with an embodiment of the present invention. Figure 6 is a graph showing the oxide polishing rate relative to the concentration of the second polishing inhibitor. Figure 7 is a graph for comparing the oxide polishing rate with respect to the type of first polishing inhibitor. Figure 8 shows the results of oxide milling relative to the type of first milling inhibitor. Figure 9 shows the zeta potential value relative to the type of first milling inhibitor. Figure 10 is a graph for comparing the change in zeta potential with respect to the type of first polishing inhibitor. 11A through 11D are cross-sectional views for explaining a method of fabricating a semiconductor device in accordance with an embodiment of the present invention.

Claims (21)

An oxide abrasive slurry, wherein the oxide abrasive slurry comprises: a first slurry comprising a ground abrasive, a dispersant for dispersing the abrasive, and a first polishing inhibitor, the first polishing inhibitor A grinding for suppressing the first material different from the oxide; and a second slurry containing a polishing accelerator for promoting the grinding of the oxide. The oxide polishing slurry of claim 1, wherein the second slurry contains a second polishing inhibitor, and the second polishing inhibitor is for suppressing the oxide and the first Grinding of a second material of different materials. The oxide abrasive slurry according to claim 1, wherein the first slurry and the second slurry are mixed at a ratio of 1:0.5 to 1:1.5. The oxide abrasive slurry according to claim 1, wherein the abrasive comprises cerium oxide particles, and is included in an amount of 0.1% by weight to 10% by weight based on the total weight of the first slurry. . The oxide abrasive slurry according to any one of claims 2, wherein a grinding selectivity between the oxide and the first material is in a range of from 100:1 to 300:1, and The polishing selectivity between the oxide and the second material is in the range of 20:1 to 60:1. The oxide polishing slurry according to claim 1, wherein the content of the first grinding inhibitor is less than the content of the polishing accelerator. The oxide polishing slurry according to claim 2, wherein the content of the first grinding inhibitor is less than the content of the second grinding inhibitor. The oxide abrasive slurry according to claim 1 or 6, wherein the first grinding inhibitor is included in an amount of 0.002% by weight to 0.02% by weight based on the total weight of the first slurry. . The oxide abrasive slurry according to claim 1 or 6, wherein the polishing accelerator is included in an amount of 0.1% by weight to 1.355% by weight based on the total weight of the second slurry. The oxide polishing slurry according to claim 2, wherein the second grinding inhibitor is included in an amount of 0.15% by weight to 1% by weight based on the total weight of the second slurry. . The oxide abrasive slurry of claim 1, wherein the first grinding inhibitor comprises a non-ionic material having both a hydrophobic group and a hydrophilic group. The oxide polishing slurry according to any one of claims 1, 2, 3, 4, 6, 7, and 11, wherein the first grinding inhibitor comprises at least one of the following: polypropylene glycol -b-polyethylene glycol-b-polypropylene glycol copolymer, polysorbate, octylphenol, polyethylene glycol, stearyl ether, nonylphenol ethoxylate, ethylene oxide, ethanol Acid or glycerol ethoxylate. The oxide abrasive slurry of claim 1, wherein the polishing accelerator comprises a monomolecular material in the family of alkanolamines having a hydroxyl group and an amine group. The oxide polishing slurry according to any one of claims 1, 2, 3, 4, 6, 7, and 13, wherein the polishing accelerator comprises at least one of the following: aminomethyl propyl Alcohol, ethanolamine, meglumine, iso-allin, methanolamine, diethylethanolamine or N-methylethanolamine. The oxide polishing slurry of claim 2, wherein the second grinding inhibitor comprises an anionic material having a carboxyl group. The oxide polishing slurry according to any one of claims 2, 7 and 15, wherein the second grinding inhibitor comprises at least one of poly(acrylic acid), poly(methacrylic acid) Alkyl esters), acrylamides, methacrylamides or ethyl-methacrylamides. A method for polishing a substrate, wherein the method for polishing a substrate comprises the steps of: preparing a substrate having an oxide layer and a heterogeneous material layer composed of a plurality of heterogeneous materials not being oxides; a slurry, the first slurry comprising an abrasive, a dispersant for dispersing the abrasive, and a first grinding inhibitor for inhibiting grinding of the first material among the plurality of heterogeneous materials; preparing a second slurry, The second slurry contains a polishing accelerator for promoting grinding of the oxide and a second polishing inhibitor for inhibiting grinding of a second material among the plurality of heterogeneous materials; and The oxide layer is ground while the slurry and the second slurry are supplied onto the substrate. The substrate polishing method of claim 17, wherein the preparing the substrate comprises the steps of: forming a first material layer composed of the first material on the substrate; Forming a second material layer composed of the second material on the material layer; forming a trench in the first material layer and the second material layer; and forming an oxide on the entire surface including the trench Floor. The substrate polishing method of claim 17 or 18, wherein in the polishing of the oxide layer, the polishing rate of the oxide layer is faster than the polishing rate of the second material, and The polishing rate of the second material is faster than the polishing rate of the first material. The substrate polishing method of claim 17, wherein the polishing selectivity between the oxide and the first material is maintained at 100:1 in the polishing of the oxide layer. Within the range of 300:1, and the grinding selectivity between the oxide and the second material is maintained in the range of 20:1 to 60:1. The substrate polishing method of claim 17 or 18, wherein in the grinding of the oxide layer, the first slurry and the second slurry are at a ratio of 1:0.5 to 1:1.5 A mixing ratio is supplied to the substrate.