KR20180017598A - Slurry composition for tungsten polishing - Google Patents

Abstract

The present invention relates to a slurry composition for polishing tungsten. According to an embodiment of the present invention, the slurry composition for polishing tungsten contains polishing particles and an oxidizer. The content of the polishing particles is 3-5 wt% in the slurry composition for polishing tungsten, and has a pH range of 2-3. According to the present invention, it is also possible to secure stability in quality in a post-process.

Description

[0001] SLURRY COMPOSITION FOR TUNGSTEN POLISHING [0002]

The present invention relates to a slurry composition for tungsten polishing.

As the design rule of the product is reduced, the aspect ratio (depth / floor width) is rapidly increasing due to the narrow width and height of the structure, and the influence of the scratches generated in the conventional 50- It affects the process more than 2 times. As a result, the influence of topography as well as scratches on the surface of the film was also enhanced. The most important factors to be considered in the polishing process are the amount of polishing and the quality of the polishing surface. Recently, as the semiconductor design rule is reduced, the importance of the quality of the polishing surface is maximized.

On the other hand, as the degree of integration of semiconductors has increased recently, a lower current leakage is required, and a high-permittivity dielectric and a metal gate structure have been devised to satisfy this demand. Aluminum has been widely used as a metal gate material in general. However, due to problems such as difficulty in complete deposition due to reduction in design rule and difficulty in polishing aluminum oxide having high hardness, much research has been conducted on using tungsten as a gate material have. However, as the material is changed from an aluminum gate to a tungsten gate, tungsten forms a topography by the tungsten crystal grain size after deposition, which causes a short between the undesired metals, resulting in a reduction in semiconductor yield. In order to improve the polishing surface quality of such tungsten, that is, polishing for topography improvement is essential for the next generation process. The slurry composition in which the topography is not improved causes tungsten over etch or unetch in the post-polishing process, resulting in a process failure or unstable operation of the device, thereby drastically lowering the semiconductor yield. In addition, it is difficult to control the surface roughness due to a high chemical etching rate instead of securing a high polishing rate by increasing the particle content. Since the surface of the tungsten film is not uniform and the surface resistance of the tungsten film is increased, Thereby deteriorating the characteristics.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and it is an object of the present invention to provide a polishing method and polishing method capable of securing a desired polishing rate and improving a topology of a tungsten surface, And to provide a slurry composition for tungsten polishing capable of improving electrical characteristics.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other matters not mentioned can be clearly understood by those skilled in the art from the following description.

According to one embodiment of the present invention, abrasive particles; And an oxidizing agent, wherein the abrasive grains are 1 wt% to 5 wt% of the slurry composition for tungsten polishing, and have a pH in the range of 2 to 3, To provide a slurry composition.

According to one aspect, the surface after polishing of tungsten using the slurry composition for tungsten polishing may have a peak to valley (Rpv) value showing surface roughness of 5 nm or less.

According to one aspect, the tungsten abrasive slurry composition provides a slurry composition for tungsten polishing, wherein the K constant value calculated by the following formula 1 satisfies 80 to 150:

[Formula 1]

K constant = (51.1 x pH value) - (4.1 x abrasive grain content).

According to one aspect, the abrasive particles include at least one selected from the group consisting of a metal oxide coated with a metal oxide, an organic or inorganic material, and a metal oxide in a colloidal state, and the metal oxide is selected from the group consisting of silica, ceria, Zirconia, alumina, titania, barium titania, germania, manganese, and magnesia.

According to one aspect, the size of the abrasive grains may be a single size particle having a size of 20 nm to 150 nm or a mixed particle of two or more kinds.

According to one aspect, the oxidant is selected from the group consisting of hydrogen peroxide, urea hydrogen peroxide, urea, percarbonate, periodate, periodate, perchlorate, perchlorate, perbromate, perbromate, perborate, perborate, permanganate, permanganate At least one selected from the group consisting of sulfuric acid, bromate, chlorate, chlorite, chromate, iodate, iodate, ammonium peroxodisulfate, benzoyl peroxide, calcium peroxide, barium peroxide, May include.

According to one aspect, the oxidizing agent may be 0.01 wt% to 5 wt% of the slurry composition for tungsten polishing.

According to one aspect, the slurry composition for tungsten polishing may be to improve the topology of tungsten.

The slurry composition for tungsten polishing according to an embodiment of the present invention satisfies the K constant value in the range of 80 to 150, so that the surface roughness is lowered, and the surface resistance is lowered, And the quality stability can be ensured even after the subsequent process. Further, the polishing rate can be maintained while improving the problem of generating surface defects such as dishing or corrosion by the chemical etching rate. Therefore, it may be to improve the topology of tungsten, and it may enable a next-generation high integration process.

1 is a surface atomic force microscope (AFM) image of a tungsten wafer after tungsten wafer polishing with the polishing slurry composition of Comparative Example 1 of the present invention.
2 is a surface atomic force microscope (AFM) image of a tungsten wafer after tungsten wafer polishing with the polishing slurry composition of Example 1 of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In addition, terms used in this specification are terms used to appropriately express the preferred embodiments of the present invention, which may vary depending on the user, the intention of the operator, or the practice of the field to which the present invention belongs. Therefore, the definitions of these terms should be based on the contents throughout this specification. Like reference symbols in the drawings denote like elements.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

Hereinafter, the slurry composition for tungsten polishing of the present invention will be specifically described with reference to examples and drawings. However, the present invention is not limited to these embodiments and drawings.

According to one embodiment of the present invention, abrasive particles; And an oxidizing agent, wherein the abrasive grains are 1 wt% to 5 wt% of the slurry composition for tungsten polishing, and have a pH in the range of 2 to 3, To provide a slurry composition.

According to one aspect, the abrasive grains may be 1 wt% to 5 wt% of the slurry composition for tungsten polishing. When the amount of the abrasive grains is less than 1 wt%, the polishing rate is decreased. When the amount of the abrasive grains is more than 5 wt%, the polishing rate is too high and the surface of the tungsten abrasive grains Surface defects can be generated by adsorption.

According to one aspect, when the pH of the slurry composition for tungsten polishing is outside the range of 2 to 3, the polishing rate of the metal film is lowered, the surface roughness is not constant, and defects such as corrosion, etching, Can be generated. The pH can be adjusted by adding the following pH adjusting agent to be described later.

According to one aspect, the surface after polishing of tungsten using the slurry composition for tungsten polishing may have a peak to valley (Rpv) value showing surface roughness of 5 nm or less. The peak-to-valley value can be measured with an atomic force microscope.

According to one aspect, the peak-to-valley (Rpv) value representing the surface roughness represents a deviation average value (arithmetic mean) of the peak and valley values with respect to the center line in the surface roughness profile of the tungsten film, (Atomic Force Microscope; AFM).

According to one aspect, the tungsten abrasive slurry composition provides a slurry composition for tungsten polishing, wherein the K constant value calculated by the following formula 1 satisfies 80 to 150:

[Formula 1]

K constant = (51.1 x pH value) - (4.1 x abrasive grain content).

The K constant value of the present invention is a relational constant that affects a static etch rate (SER) value. In this formula 1, the value of the abrasive grain content is substituted as it is. For example, when the abrasive grain content is 3% by weight, "3" is substituted into Equation 1.

The surface-to-minute static etching rate (SER) value of the surface of the tungsten using the slurry composition for tungsten polishing may be 150 A / min or less.

The static etching rate (SER) value can be measured in the following manner. The tungsten wafer was immersed in a 5 cm thick 2 cm ² tungsten coupon wafer in a container containing 30 g of the slurry composition for tungsten polishing at 60 DEG C for 10 minutes. A 4-point probe is used to measure the thickness of the tungsten wafer before and after immersion, at 5 mm intervals from the center of the wafer, and then calculate the static etching rate per minute (SER). The static etching rate (SER) value can be calculated by the following Equation 2, and the unit is A / min.

[Formula 2]

The slurry composition for tungsten polishing according to one embodiment of the present invention satisfies the K constant value in the range of 80 to 150, so that the surface roughness is lowered. As a result, the surface resistance is low, the current loss is reduced, and the electrical characteristics can be improved. Further, the polishing rate can be maintained while improving the problem of generating surface defects such as dishing or corrosion by the chemical etching rate. Therefore, it may be to improve the topology of tungsten, and it may enable a next-generation high integration process.

According to one aspect, the abrasive particles include at least one selected from the group consisting of a metal oxide coated with a metal oxide, an organic or inorganic material, and a metal oxide in a colloidal state, and the metal oxide is selected from the group consisting of silica, ceria, Zirconia, alumina, titania, barium titania, germania, manganese, and magnesia.

According to one aspect, the size of the abrasive grains may be a single size particle having a size of 20 nm to 150 nm or a mixed particle of two or more kinds. If the size of the abrasive grains is less than 20 nm, the polishing rate may be lowered. If the abrasive grains are larger than 150 nm, excessive polishing may occur, and dishing, surface defects, and polishing rate may be difficult to control.

According to one aspect, the abrasive grains may have a particle size controlled by controlling calcination conditions and / or milling conditions, and may be mixed with two kinds of particles to have a bimodal particle size distribution. Or may have a particle size distribution in which three kinds of particles are mixed and show three peaks. The relatively large abrasive grains and the relatively small abrasive grains can be mixed to have better dispersibility and the effect of reducing the scratch on the wafer surface can be expected.

According to one aspect, the oxidant is selected from the group consisting of hydrogen peroxide, urea hydrogen peroxide, urea, percarbonate, periodate, periodate, perchlorate, perchlorate, perbromate, perbromate, perborate, perborate, permanganate, permanganate At least one selected from the group consisting of sulfuric acid, bromate, chlorate, chlorite, chromate, iodate, iodate, ammonium peroxodisulfate, benzoyl peroxide, calcium peroxide, barium peroxide, May include.

According to one aspect, the oxidizing agent may be 0.01 wt% to 5 wt% of the slurry composition for tungsten polishing. When the oxidizing agent is less than 0.01 wt% in the slurry composition for tungsten polishing, the polishing rate and the etching rate for tungsten may be lowered. When the oxidizing agent is more than 5 wt%, the oxide film on the tungsten surface becomes hard, The oxide film grows and the topology is not good due to corrosion and erosion of tungsten.

The slurry composition for tungsten polishing according to an embodiment of the present invention may further include a water-soluble polymer, an etching control agent, or both.

According to one aspect, the water-soluble polymer may be a polymer compound having a weight average molecular weight of 1,000,000 or less, and preferably a compound having a weight average molecular weight of 25,000 to 1,000,000 or less. When the water-soluble polymer has a weight average molecular weight of more than 1,000,000, solubility, stability of particle dispersion and polishing property may be lowered.

According to one aspect, the water-soluble polymer may include acrylic acid, an acrylic acid copolymer, a sulfonic acid and a salt or a derivative thereof, and examples thereof include polyacrylic acid, polyacrylic acid copolymer, polymethacrylic acid, polyacrylic maleic acid, Acrylic acid copolymers, polyacrylic acid / acrylic acid copolymers, polyacrylic acid / sulfonic acid copolymers, polysulfonic acid / acrylamide copolymers, polysulfonic acid, polystyrenesulfonic acid, polyvinylsulfonic acid, polyacrylamidomethylpropanesulfonic acid, poly- p-methylstyrenesulfonic acid, and salts thereof, and the like.

According to one aspect, the water-soluble polymer may be 0.01 wt% to 0.5 wt% of the slurry composition for tungsten polishing. If the amount of the water-soluble polymer is less than 0.01% by weight in the slurry composition for tungsten polishing, there is a problem that the adsorptivity is lowered. If the water-soluble polymer is more than 0.5% by weight, the tungsten polishing rate and stability may be lowered.

In general, tungsten is easy to adhere to impurities due to its nature, and is easily dissolved. However, when tungsten is easily re-adhered, it is likely to remain as a main factor that can cause defects in the subsequent process. To solve this problem, an etching control agent may be included.

According to one aspect, the etch control agent is selected from the group consisting of butyric acid, citric acid, tartaric acid, succinic acid, oxalic acid, acetic acid, adipic acid, capric acid, caproic acid, caprylic acid, carboxylic acid, glutaric acid, glutamic acid, glycolic acid, But are not limited to, glycolic, formic, mandelic, fumaric, lactic, malic, maleic, malonic, myristic, At least one selected from the group consisting of valeric acid, benzoic acid, phenylacetic acid, naphthoic acid, aspartic acid, amino acid and ethylenediaminetetraacetic acid.

According to one aspect, the etching control agent may be 0.005 wt% to 0.2 wt% of the slurry composition for tungsten polishing. When the etching control agent is less than 0.005% by weight in the slurry composition for tungsten polishing, the polishing rate of the tungsten film may be lowered and the desired polishing rate may not be achieved, and the surface may not be uniformly polished due to increased surface roughness, And if it is more than 0.2% by weight, tungsten film tends to be hardened and the grain stability of the tungsten polishing slurry composition may be reduced.

The slurry composition for tungsten polishing according to an embodiment of the present invention may further include a pH adjusting agent to prevent corrosion of a metal or a polishing machine and to realize a pH range where metal oxidation easily occurs. The pH adjusting agent may be at least one selected from the group consisting of hydrochloric acid, phosphoric acid, sulfuric acid, hydrobromic acid, hydrobromic acid, salicylic acid, acetic acid, An acidic substance comprising at least any one selected from the group consisting of pimelic acid, benzoic acid, succinic acid, phthalic acid, butyric acid, glutaric acid, glutamic acid, glycolic acid, lactic acid, aspartic acid and tartaric acid and salts thereof; And at least one selected from the group consisting of ammonia, ammonium methyl propanol (AMP), tetramethyl ammonium hydroxide (TMAH), potassium hydroxide, sodium hydroxide, magnesium hydroxide, rubidium hydroxide, cesium hydroxide, sodium hydrogencarbonate, sodium carbonate, , And a basic substance including at least one selected from the group consisting of:

According to one aspect, the slurry composition for tungsten polishing may be to improve the topology of tungsten. By using a slurry composition for tungsten polishing that exhibits a K constant value in the range of 80 to 150, which meets the conditions of the present invention, it is possible to improve the topology of tungsten and achieve the desired polishing rate, It has the advantages of reduced surface defects, less residual particles, and excellent polishing efficiency, thereby improving yields due to metal shorts and etch failures caused by the topology and improving the chemical mechanical polishing process And the like.

Hereinafter, the present invention will be described in detail with reference to the following examples and comparative examples. However, the technical idea of the present invention is not limited or limited thereto.

Example

[ Example  One]

3% by weight of colloidal silica abrasive grains having a particle size of 100 nm and 0.5% by weight of hydrogen peroxide as an oxidizing agent were mixed and adjusted to pH 2 with ammonium hydroxide (NH ₄ OH) to prepare a tungsten polishing slurry composition having a pH of 2.

[ Example  2]

In Example 1, a slurry composition for tungsten polishing was prepared in the same manner as in Example 1, except that 5 wt% of silica abrasive grains were added.

[ Example  3]

In Example 1, a slurry composition for tungsten polishing was prepared in the same manner as in Example 1, except that 3.3 wt% of silica abrasive grains were added and adjusted to pH 2.2 with ammonium hydroxide (NH ₄ OH).

[ Example  4]

In Example 3, a slurry composition for tungsten polishing was prepared in the same manner as in Example 3 except that silica abrasive grains were added in an amount of 4.7% by weight.

[ Example  5]

In Example 1, a slurry composition for tungsten polishing was prepared in the same manner as in Example 1, except that silica abrasive grains were added in an amount of 3.6 weight% and adjusted to pH 2.4.

[ Example  6]

In Example 5, a slurry composition for tungsten polishing was prepared in the same manner as in Example 5, except that silica abrasive grains were added in an amount of 4.4% by weight.

[ Example  7]

In Example 1, a slurry composition for tungsten polishing was prepared in the same manner as in Example 1, except that 3.9 wt% of silica abrasive grains were added and adjusted to pH 2.6.

[ Example  8]

In Example 7, a slurry composition for tungsten polishing was prepared in the same manner as in Example 7 except that silica abrasive grains were added in an amount of 4.1 wt%.

[ Example  9]

In Example 1, a slurry composition for tungsten polishing was prepared in the same manner as in Example 1, except that silica abrasive grains were added in an amount of 4.2 wt% and adjusted to a pH of 2.8.

[ Example  10]

A slurry composition for tungsten polishing was prepared in the same manner as in Example 9 except that 3.8% by weight of silica abrasive grains were added.

[ Example  11]

A slurry composition for tungsten polishing was prepared in the same manner as in Example 1, except that the pH was adjusted to 3 in Example 1.

[ Example  12]

In Example 9, a slurry composition for tungsten polishing was prepared in the same manner as in Example 11, except that 5 wt% of silica abrasive grains were added.

[ Comparative Example  One]

2.5% by weight of colloidal silica abrasive grains having a particle size of 100 nm and 0.5% by weight of hydrogen peroxide as an oxidizing agent were mixed and the pH was adjusted with ammonium hydroxide (NH ₄ OH) to prepare a tungsten polishing slurry composition having a pH of 3.5 .

[ Comparative Example  2]

In Comparative Example 1, a slurry composition for tungsten polishing was prepared in the same manner as in Comparative Example 1 except that 2.9 wt% of silica abrasive grains were added.

[ Comparative Example  3]

A slurry composition for tungsten polishing was prepared in the same manner as in Comparative Example 1, except that in Comparative Example 1, the pH was adjusted to 4.

[ Comparative Example  4]

In Comparative Example 3, a slurry composition for tungsten polishing was prepared in the same manner as in Comparative Example 3 except that 2.9 wt% of silica abrasive grains were added.

The polishing slurry compositions of Examples 1 to 12 and Comparative Examples 1 to 4 of the present invention were used to polish tungsten wafers under the following polishing conditions.

[Polishing rate (RR) measuring method]

1. Feeding rate: 200 ml / min.

2. Pressure: 3 psi

3. CMP time: 1 min.

4.

[Peak-to-valley (Rpv) measuring method]

Measuring equipment Model: XE-100

Scan Size (Scan Size): 10 탆

Table 1 shows the abrasive particle types, the abrasive particle content, the pH of the slurry composition, the type of the oxidizing agent, the content of the oxidizing agent, the K constant value and the polishing rate (Roving Ratio (RR)) of Examples 1 to 12 and Comparative Examples 1 to 4 of the present invention ) Value and a peak-to-valley (Rpv) value representing surface roughness.

grinding
particle content
(weight%) pH Oxidant content
(weight%) K constant RR
(Å / min) Rpv
(nm) Example 1 100 nm
Silica 3 2 Hydrogen peroxide 0.5 89.9 156 2.68 Example 2 100 nm
Silica 5 2 Hydrogen peroxide 0.5 81.7 144 2.33 Example 3 100 nm
Silica 3.3 2.2 Hydrogen peroxide 0.5 98.9 164 2.72 Example 4 100 nm
Silica 4.7 2.2 Hydrogen peroxide 0.5 93.2 156 2.24 Example 5 100 nm
Silica 3.6 2.4 Hydrogen peroxide 0.5 107.9 152 2.89 Example 6 100 nm
Silica 4.4 2.4 Hydrogen peroxide 0.5 104.6 164 2.91 Example 7 100 nm
Silica 3.9 2.6 Hydrogen peroxide 0.5 116.9 180 3.12 Example 8 100 nm
Silica 4.1 2.6 Hydrogen peroxide 0.5 116.1 196 3.05 Example 9 100 nm
Silica 4.2 2.8 Hydrogen peroxide 0.5 125.9 180 3.13 Example 10 100 nm
Silica 3.8 2.8 Hydrogen peroxide 0.5 127.5 188 3.11 Example 11 100 nm
Silica 3 3 Hydrogen peroxide 0.5 141 188 3.25 Example 12 100 nm
Silica 5 3 Hydrogen peroxide 0.5 132.8 172 3.17 Comparative Example 1 100 nm
Silica 2.5 3.5 Hydrogen peroxide 0.5 168.6 201 5.41 Comparative Example 2 100 nm
Silica 2.9 3.5 Hydrogen peroxide 0.5 167.0 203 5.14 Comparative Example 3 100 nm
Silica 2.5 4 Hydrogen peroxide 0.5 194.2 212 6.04 Comparative Example 4 100 nm
Silica 2.9 4 Hydrogen peroxide 0.5 192.5 213 5.96

As shown in Table 1, the slurry compositions for tungsten polishing according to Examples 1 to 12 of the present invention had a desired polishing rate (RR) value of 150 nm to 200 nm and a peak-to-valley value Rpv ) Is lower than in the case of using the slurry compositions of Comparative Examples 1 to 4. On the other hand, in Comparative Examples 1 to 3, it can be seen that the polishing rate (RR) value according to chemical etching increases, but it can be confirmed that the roughness value is increased.

FIG. 1 is a surface atomic force microscope (AFM) image of a tungsten wafer after polishing a tungsten wafer with the polishing slurry composition of Comparative Example 1 of the present invention, and FIG. 2 is a cross- Surface atomic force microscope (AFM) image. Referring to FIGS. 1 and 2, it can be seen that the surface roughness of the tungsten wafer of Example 1 is remarkably improved as compared with the surface of the tungsten wafer of Comparative Example 1.

As in Comparative Examples 1 to 4, when the K-constant value increases to more than 150 and the peak-to-valley value Rpv is high, the surface resistance of the tungsten film is high and heat is generated on the surface, Quality stability can not be ensured even in a post-process.

On the other hand, as in Examples 1 to 12 of the present invention, when the K-constant value is low in the range of 80 to 150 and the peak-to-valley Rpv is low, the surface resistance is low and the current loss is small, And the quality stability can be ensured even after the subsequent process.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible. Therefore, the scope of the present invention should not be limited by the described embodiments, but should be determined by the equivalents of the appended claims, as well as the appended claims.

Claims (8)

Abrasive particles; And
Oxidant;
≪ RTI ID = 0.0 > a < / RTI > tungsten abrasive slurry composition,
The abrasive grains are 1 wt% to 5 wt% of the slurry composition for tungsten polishing,
lt; RTI ID = 0.0 > pH < / RTI >
Slurry composition for tungsten polishing.
The method according to claim 1,
Wherein the surface after polishing the tungsten using the slurry composition for tungsten polishing has a peak to valley (Rpv) value showing surface roughness of 5 nm or less.
The method according to claim 1,
Wherein the slurry composition for tungsten polishing satisfies a K constant value calculated by the following formula 1 from 80 to 150:
[Formula 1]
K constant = (51.1 x pH value) - (4.1 x abrasive grain content).
The method according to claim 1,
The above-
At least one selected from the group consisting of a metal oxide coated with a metal oxide, an organic or inorganic material, and a metal oxide in a colloidal state,
Wherein the metal oxide comprises at least one selected from the group consisting of silica, ceria, zirconia, alumina, titania, barium titania, germania, manganese, and magnesia.
The method according to claim 1,
Wherein the size of the abrasive grains is a single size particle having a size of 20 nm to 150 nm or a mixed particle of two or more kinds.
The method according to claim 1,
The oxidizing agent may be at least one selected from the group consisting of hydrogen peroxide, urea hydrogen peroxide, urea, percarbonate, periodate, periodate, perchlorate, perchlorate, perbromate, perbromate, perborate, perborate, permanganate, permanganate, persulfate, At least one selected from the group consisting of chlorate, chlorite, chromate, iodate, iodate, ammonium peroxodisulfate, benzoyl peroxide, calcium peroxide, barium peroxide, sodium peroxide and peroxide , A slurry composition for tungsten abrasion.
The method according to claim 1,
Wherein the oxidizing agent is 0.01 wt% to 5 wt% of the slurry composition for tungsten polishing.
The method according to claim 1,
Wherein the slurry composition for tungsten polishing improves the topology of tungsten.

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