KR101340551B1 - CMP slurry composition for selective polishing of silicon nitride - Google Patents

Abstract

The present invention relates to a CMP slurry composition capable of selectively polishing silicon nitride by increasing the polishing rate of silicon nitride relative to silicon oxide and / or polysilicon.

Description

CMP slurry composition for selective polishing of silicon nitride

The present invention relates to a CMP slurry composition that selectively polishes silicon nitride (SiN). More specifically, the present invention includes a (meth) acrylate copolymer and a pyridine-based compound to increase the polishing rate of silicon nitride relative to silicon oxide (SiO 2) and / or polysilicon, thereby selectively polishing the silicon nitride CMP It relates to a slurry composition.

The CMP process refers to a process of smoothly polishing a semiconductor wafer surface using a slurry containing an abrasive and various compounds while performing orbital motion by contacting the polishing pad. The slurry used in the CMP process contains a compound such as an oxidizer, a dispersant, a stabilizer, a pH adjuster, a selectivity adjuster, and metal oxides such as silica, alumina, ceria, zirconia, titania, and the like.

Compounds including the oxidant and the like act on the target film to be polished to soften the parts to be smoothly removed and to form a protective film on the parts not to be polished to provide excellent flatness after the CMP process. The metal oxide acts on the film to be polished to remove the portion to be polished at a high speed, thereby increasing the activity of the compound in the slurry on the film. However, since the polishing rate between films is different depending on the type of metal oxide, it should be selectively used according to the type of film to be polished.

Conventionally, CMP slurry compositions have been mainly used for polishing silicon oxide films using a silicon nitride film as a polishing stop film. The silicon nitride film is used for protecting the underlying structure for the formation of metal wirings in a semiconductor manufacturing process. First, the silicon nitride layer is made by applying chemical vapor deposition on the entire surface of the wafer, and then the excess portion is removed. In general, a method of removing silicon nitride may use a dry ethching or CMP process.

The dry etching method has a disadvantage in that the process is complicated and residues are generated after etching, thereby lowering the yield of the device. In addition, since a multi-step process is required to remove only one silicon nitride film, a lot of time and money are consumed. In addition, the removal of silicon nitride by dry etching may adversely affect the lower film quality, and materials remaining on the wafer after the process may cause fatal defects in the semiconductor circuit.

On the other hand, the CMP method simplifies the process and improves yield, but the low polishing rate for silicon nitride can lead to longer process times and result in process defects such as erosion and dishing. . Therefore, there is a need to develop a slurry composition having a high polishing rate for silicon nitride. However, the high polishing rate for silicon nitride alone makes it difficult to apply to actual devices. Although the polishing rate for silicon nitride is remarkably high, process defects such as dishing or erosion are more likely to occur if polishing for silicon oxide and polysilicon is performed at the same rate.

Therefore, there is a need to develop a CMP slurry composition that can polish not only a high polishing rate for silicon nitride but also a high selectivity to silicon nitride relative to silicon oxide or polysilicon.

It is an object of the present invention to provide a CMP slurry composition capable of selectively polishing silicon nitride relative to silicon oxide.

Another object of the present invention is to provide a CMP slurry composition capable of selectively polishing silicon nitride relative to polysilicon.

It is still another object of the present invention to provide a CMP slurry composition capable of selectively polishing silicon nitride relative to silicon oxide and polysilicon.

The CMP slurry composition of the present invention may have a ratio of the polishing rate of silicon nitride to silicon oxide of 5: 1 or more and the ratio of the polishing rate of silicon nitride to polysilicon of 5: 1 or more.

In one embodiment, the CMP slurry composition may include ultrapure water, an abrasive, an iron ion compound, a stabilizer, a pyridine compound, and a (meth) acrylate copolymer.

In one embodiment, the pyridine-based compound is 3-hydroxypyridine, 2-hydroxypyridine, pyridine-2-carboxylic acid, pyridine-3-carboxylic acid, pyridine-4-carboxylic acid, pyridine-2,3-carboxylic acid, pyridine- At least one selected from the group consisting of 2-amine, pyridine-3-amine, pyridine-2-carboxaldehyde and pyridine-3-carboxaldehyde.

In one embodiment, the (meth) acrylate copolymer is polyacrylamide, polymethyl (meth) acrylate, poly (meth) acrylic acid, metal salt or ammonium salt of poly acrylic acid, poly (acrylamide-co-acrylic acid), It may be at least one selected from the group consisting of poly (acrylic acid-co-maleic acid) and poly (methyl (meth) acrylate-co-butyl (meth) acrylate).

The present invention provides a CMP slurry composition capable of selectively polishing silicon nitride relative to silicon oxide. In addition, the present invention provides a CMP slurry composition capable of selectively polishing silicon nitride relative to polysilicon. The present invention also provides a CMP slurry composition capable of selectively polishing silicon nitride relative to silicon oxide and polysilicon.

In the CMP slurry composition of the present invention, the ratio of the polishing rate of silicon nitride to silicon oxide may be 5: 1 or more, and the ratio of the polishing rate of silicon nitride to polysilicon may be 5: 1 or more. Preferably, the ratio of the polishing rate of silicon nitride to silicon oxide may be 10: 1 or more, and the ratio of the polishing rate of silicon nitride to polysilicon may be 10: 1 or more.

When the CMP slurry composition is applied to a semiconductor wafer, the polishing rate of each component included in the semiconductor wafer may vary depending on the physical properties of the component, the type of the abrasive, and the content and type of the component included in the slurry composition. The present invention is characterized by increasing the polishing rate of silicon nitride and / or polysilicon while increasing the polishing rate of silicon nitride, thereby increasing the selectivity of the polishing rate of silicon nitride with respect to silicon oxide and / or polysilicon.

Such a CMP slurry composition of the present invention may include ultrapure water, an abrasive, an iron ion compound, a stabilizer, a pyridine compound, and a (meth) acrylate copolymer.

abrasive

The abrasive may use an abrasive commonly used in CMP slurry compositions. For example, the abrasive may be a metal oxide synthesized wet or dry. Specific examples may be at least one selected from the group consisting of ceria, silica, alumina, titania and zirconia synthesized wet or dry. In addition, two or more metal oxides coexist in one particle. Specific examples may include ceria coated or doped silica, zirconia coated with rare earth metal, and the like. Preferably, ceria may be used as the abrasive. Ceria can provide high polishing rates for silicon nitride relative to silicon oxide when used with the following iron ionic compounds at acidic pH.

The abrasive may be added in an appropriate amount depending on the dispersion stability of the CMP slurry composition, the polishing rate, and the surface properties of the abrasive. For example, the abrasive can be added at 0.01-50% by weight of the total CMP slurry composition. Within this range, the polishing rate of silicon nitride and the polishing rate and selectivity of silicon oxide and / or polysilicon can be effectively controlled. Preferably 0.1-25% by weight.

Iron ion compound

The CMP slurry composition of the present invention is intended to increase the selectivity of the polishing rate for silicon nitride relative to silicon oxide and / or polysilicon. For this purpose, the polishing rate of silicon nitride should be high basically. The iron ion compound may oxidize silicon nitride to increase the polishing rate of silicon nitride.

Examples of the iron ion compound may be an iron trivalent ion compound or a complex thereof. Specific examples include inorganic iron salts such as iron nitrate, iron phosphate, iron chloride, ferrous sulfate, ferrous sulfate, iron perchlorate, propylenediaminetetraacetate iron salt (Fe-PDTA), ethylenediaminetetraacetate iron salt (Fe-EDTA), and ammonium sheet. Organic iron salts such as Fe-ammonium citrate, iron d-gluconate, iron perchlorate, and the like, but are not limited thereto.

The iron ion compound may be included at a concentration of 0.01-10% by weight in the CMP slurry composition. Within this range, the polishing rate of silicon nitride may be high and the selectivity of the polishing rate for silicon nitride relative to silicon oxide and / or polysilicon may be high. Preferably it may be included in 0.05-5% by weight.

Stabilizer

In the CMP slurry composition of the present invention, the iron ion compound is used to increase the polishing rate of silicon nitride. However, the iron ion compound may lower the polishing rate of silicon nitride by decreasing stability when the pH is high. Stabilizers can increase the polishing rate of silicon nitride by stabilizing the iron ion compound.

Examples of stabilizers can be organic acids, inorganic acids or salts thereof and the like.

The organic acid may be an organic compound having a carboxyl group, a sulfone group, or a sulfinic acid group which is an acidic functional group. For example, monocarboxylic acid including acetic acid, oxalic acid, tartaric acid, dicarboxylic acid including malic acid, maleic acid, citric acid and the like, sulfonic acid including P-toluenesulfonic acid and the like, sulfonic acid including p-toluenesulfonic acid and the like Etc., but it is not limited to these. In addition, the organic acid may be an amino acid having both a carboxyl group and an amine group in one molecule. The amino acid may be at least one selected from the group consisting of glycine, isoleucine, leucine, lysine, phenylalanine, methionine, threonine, tryptophan, valine, alanine, arginine, cysteine, glutamine, histidine, proline, serine and tyrosine, It is not limited to these.

The inorganic acid may mean an acid including a nonmetal such as chlorine, sulfur, nitrogen, and phosphorus. For example, hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid and the like, but are not limited to these.

The organic acid and the inorganic acid may be used alone or in combination of two or more for stabilizing the iron ion compound, and may be used together with the organic acid and the inorganic acid.

Stabilizers may be included at concentrations of 0.001-5% by weight in the CMP slurry composition. Within this range, the polishing rate of silicon nitride may be high and the selectivity of the polishing rate for silicon nitride relative to silicon oxide and / or polysilicon may be high. Preferably it may be included in 0.01-1% by weight.

( Meta ) Acrylate series  Copolymer

The CMP slurry composition of the present invention is intended to increase the selectivity of the polishing rate for silicon nitride relative to silicon oxide and / or polysilicon. This requires lowering the polishing rate for polysilicon. The (meth) acrylate copolymer has a (meth) acrylate functional group and thus can be prevented from oxidizing and polishing the polysilicon by effectively adsorbing the polysilicon.

The (meth) acrylate copolymer may have a weight average molecular weight of less than 10,000 g / mol, preferably 100-10,000 g / mol. Of the (meth) acrylate copolymer may be a homopolymer of a monomer having a (meth) acrylate group or a heteropolymer of a monomer having a (meth) acrylate group and another type of monomer. For example, polyacrylamide, polymethyl (meth) acrylate, poly (meth) acrylic acid, metal salts or ammonium salts of polyacrylic acid, poly (acrylamide-co-acrylic acid), poly (acrylic acid-co-maleic acid) and poly It may be one or more selected from the group consisting of (methyl (meth) acrylate-co-butyl (meth) acrylate), but is not limited thereto.

The (meth) acrylate copolymer may be included at a concentration of 0.001-5% by weight in the CMP slurry composition. Within this range, the polishing rate of silicon nitride may be high and the selectivity of the polishing rate for silicon nitride may be higher than that of polysilicon. Preferably it may be included in 0.005-1.0% by weight.

Pyridine compounds

The CMP slurry composition of the present invention is intended to increase the selectivity of the polishing rate for silicon nitride relative to silicon oxide and / or polysilicon. The pyridine-based compound can lower the polishing rate for silicon oxide by forming a protective film for silicon oxide, thereby increasing the selectivity of the polishing rate for silicon nitride.

The pyridine-based compound may be a compound having a structure in which at least one functional group selected from the group consisting of a hydroxyl group, a carboxylic acid group, an amine group and a carboxaldehyde group is bonded to at least one pyridine. For example, the pyridine-based compound may be 3-hydroxypyridine, 2-hydroxypyridine, pyridine-2-carboxylic acid, pyridine-3-carboxylic acid, pyridine-4-carboxylic acid, pyridine-2,3-carboxylic acid, pyridine-2- It may be one or more selected from the group consisting of amines, pyridin-3-amines, pyridine-2-carboxaldehydes and pyridine-3-carboxaldehydes, but is not limited thereto.

The pyridine-based compound may be included at a concentration of 0.001-5% by weight in the CMP slurry composition. Within the above range, within the above range, the polishing rate of silicon nitride may be high and the selectivity of the polishing rate for silicon nitride relative to silicon oxide may be high. Preferably it may be included in 0.01-1% by weight.

In the CMP slurry composition of the present invention, the (meth) acrylate copolymer and the pyridine-based compound were found to be able to independently lower the polishing rate of polysilicon and silicon oxide without interfering with each other.

In the CMP slurry composition of the present invention, the (meth) acrylate copolymer: pyridine compound is preferably 10: 1 to 1:10, and more preferably 5: 1 to 1: 5. The mixing ratio of the two materials can be appropriately adjusted in consideration of the polishing conditions and the polishing efficiency within the above range.

The CMP slurry composition of the present invention is preferably pH 7 or less for stabilizing the iron ion compound affecting the polishing rate of silicon nitride. Within this range, the iron ion compound affecting the polishing rate of silicon nitride is stable, so that the polishing rate of silicon nitride can be high, the slurry can be stable for a long time, and the polishing rate of silicon oxide is also not increased.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

Details that are not described herein will be omitted since the description can be inferred by those skilled in the art.

Example

For the slurry compositions prepared in the following Examples and Comparative Examples, the polishing rates for silicon oxide, silicon nitride, and polysilicon were measured according to the following method.

1.Grinding machine: Model Mirra (AMAT company)

2. Polishing condition

Pad: IC1010 / SubaIV Stacked (Rodel)

Platen speed: 133 rpm

Head speed: 111 rpm

Pressure: 3 psi

-Slurry inflow rate: 200ml / min

3. Polishing target

As the sample wafer, silicon nitride, silicon oxide, and polysilicon wafers in a flat state were used. Silicon nitride wafers are deposited by PE-TEOS 1000 Å on silicon wafers and then 1800 소 silicon nitride by chemical vapor deposition. Silicon oxide wafers are PE-TEOS 10000Å deposited on silicon wafers. Polysilicon wafers are deposited on a silicon wafer with polysilicon 3000 microseconds.

Example  One

50 g of ceria powder was dispersed in 10 kg of ultrapure water, and 100 g of Fe-ammonium citrate was added. 100 g of malic acid was added to the resulting slurry, and the pH was adjusted to 3 using nitric acid. It was then stirred for 30 minutes and passed through a 1 micron filter. Poly (acrylic acid-co-maleic acid) (Mw: 3000 g / mol) and 3-hydroxypyridine were then added at the concentrations listed in Table 1 to prepare a slurry. Then, the polishing rate of silicon nitride, silicon oxide and polysilicon was measured according to the polishing rate measuring method described above, and the results are shown in Table 2 below.

Example  2-9

Slurry was carried out in the same manner as in Example 1, except that poly (acrylic acid-co-maleic acid) (Mw: 3000 g / mol) and 3-hydroxypyridine were added in the components and concentrations shown in Table 1 below. Was prepared, and the polishing rates of silicon nitride, silicon oxide and polysilicon were measured according to the polishing rate measuring method described above, and the results are shown in Table 2 below.

Comparative Example  1-3

A slurry was prepared in the same manner as in Example 1, except that poly (acrylic acid-co-maleic acid) (Mw: 3000 g / mol) and 3-hydroxypyridine were not used, and the polishing rate described above According to the measurement method, the polishing rates of silicon nitride, silicon oxide and polysilicon were measured, and the results are shown in Table 2 below.

(Meth) acrylate-based copolymer Pyridine compounds Kinds Content (% by weight) Kinds Content (% by weight) Example 1 Poly (acrylic acid-co-maleic acid) 0.5 3-hydroxypyridine 0.5 Example 2 Poly (acrylic acid-co-maleic acid) 0.1 3-hydroxypyridine 0.5 Example 3 Poly (acrylic acid-co-maleic acid) 0.5 3-hydroxypyridine 0.1 Example 4 Polyacrylamide 0.5 Pyridine-2-carboxylic acid 0.5 Example 5 Polyacrylamide 0.1 Pyridine-2-carboxylic acid 0.5 Example 6 Polyacrylamide 0.5 Pyridine-2-carboxylic acid 0.1 Example 7 Poly (meth) acrylic acid 0.5 Pyridine-2-carboxylic acid 0.5 Example 8 Poly (meth) acrylic acid 0.1 Pyridine-2-carboxylic acid 0.5 Example 9 Poly (meth) acrylic acid 0.5 Pyridine-2-carboxylic acid 0.1 Comparative Example 1 - - - - Comparative Example 2 Poly (acrylic acid-co-maleic acid) 0.5 - - Comparative Example 3 - - 3-hydroxypyridine 0.5

Silicon Nitride Polishing Speed
(Å / min) Silicon Oxide Polishing Rate
(Å / min) Polysilicon Polishing Speed
(Å / min) Polishing speed ratio of silicon nitride to silicon oxide Polishing speed ratio of silicon nitride to polysilicon Example 1 830 75 55 11: 1 15: 1 Example 2 850 76 60 11.18: 1 14.17: 1 Example 3 845 80 60 10.56: 1 14.17: 1 Example 4 800 72 55 11.11: 1 15.45: 1 Example 5 810 72 60 11.25: 1 14.17: 1 Example 6 820 75 56 10.93: 1 15.18: 1 Example 7 900 71 66 12.68: 1 12.88: 1 Example 8 920 75 64 12.27: 1 13.28: 1 Example 9 910 70 69 13: 1 12.32: 1 Comparative Example 1 850 250 300 3.4: 1 2.8: 1 Comparative Example 2 830 70 180 11.86: 1 4.61: 1 Comparative Example 3 840 255 45 3.29: 1 18.67: 1

As shown in Table 2, the composition of Examples 1-9 according to the present invention can be seen that the selectivity of the polishing rate for silicon oxide and silicon nitride is significantly higher. On the other hand, Comparative Example 1, which does not include a pyridine compound and a (meth) acrylate copolymer, shows that the selectivity of polishing rate is low for both silicon oxide and silicon nitride. In addition, it can be seen that Comparative Example 2-3 of the composition including only one of the pyridine compound and the (meth) acrylate copolymer cannot increase both the selectivity of the polishing rate for silicon oxide and silicon nitride.

Claims (9)

The ratio of the polishing rate of silicon nitride to silicon oxide is 5: 1 or more and the ratio of the polishing rate of silicon nitride to polysilicon is 5: 1 or more,
Ultrapure water;
abrasive;
Iron ion compounds;
Stabilizers;
Pyridine-based compounds; And
CMP slurry composition containing a (meth) acrylate type copolymer.
The CMP slurry composition according to claim 1, wherein the CMP slurry composition has a ratio of polishing rate of silicon nitride to silicon oxide of 10: 1 or more and a ratio of polishing rate of silicon nitride to polysilicon of 10: 1 or more.
delete The CMP slurry composition of claim 1, wherein the (meth) acrylate copolymer: pyridine compound is mixed in a range of 10: 1 to 1:10.
The CMP slurry composition of claim 1, wherein the (meth) acrylate copolymer: pyridine compound is mixed in a range of 5: 1 to 1: 5.
The CMP slurry composition according to claim 1, wherein the abrasive is at least one selected from the group consisting of ceria, silica, alumina, titania, zirconia, silica coated with or doped with ceria, and zirconia coated with rare earth metals. .
The method of claim 1, wherein the stabilizer is acetic acid, oxalic acid, tartaric acid, malic acid, maleic acid, citric acid, P-toluenesulfonic acid, p-toluenesulfonic acid, glycine, isoleucine, leucine, lysine, phenylalanine, methionine, threonine, tryptophan, CMP slurry composition, characterized in that at least one selected from the group consisting of valine, alanine, arginine, cysteine, glutamine, histidine, proline, serine, tyrosine, hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid.
According to claim 1, wherein the pyridine-based compound is 3-hydroxypyridine, 2-hydroxypyridine, pyridine-2-carboxylic acid, pyridine-3-carboxylic acid, pyridine-4-carboxylic acid, pyridine-2,3-carboxylic acid, pyridine CMP slurry composition, characterized in that at least one selected from the group consisting of 2-amine, pyridine-3-amine, pyridine-2-carboxaldehyde and pyridine-3-carboxaldehyde.
According to claim 1, wherein the (meth) acrylate copolymer is polyacrylamide, polymethyl (meth) acrylate, poly (meth) acrylic acid, metal salt or ammonium salt of poly acrylic acid, poly (acrylamide-co-acrylic acid) CMP slurry composition, characterized in that at least one selected from the group consisting of poly (acrylic acid-co-maleic acid) and poly (methyl (meth) acrylate-co-butyl (meth) acrylate).