JPH1180708A - Composition for polishing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition for polishing, having a high polishing rate and capable of forming a polished surface excellent in uniformity. SOLUTION: This composition for polishing comprises (1) water, (2) a polishing material, (3) at least one anion selected from the group consisting of nitrate, nitrite, chloride, perchlorate, chlorate, chlorite, hypochlorite, borate, perborate, sulfate, sulfite, persulfate, phosphate, phosphite, hypophosphite, silicate, organic acid radicals and ions of the hydroacids thereof or a mixture thereof and (4) at least one cation selected from the group consisting of ammonium ions, alkali metallic ions and alkaline earth metallic ions. In this case, the total amount of the cation (4) is 0.001-0.15 mol/L.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing composition used for polishing various industrial products such as semiconductors, photomasks, bases for various types of memory hard disks and synthetic resins or members thereof, and more particularly to device wafers in the semiconductor industry and the like. The present invention relates to a polishing composition suitable for surface flattening processing.

More specifically, the present invention
In the polishing of a silicon dioxide film, which is an interlayer insulating film and an insulating film for element isolation, to which the P technique (described later in detail) is applied, a high polishing rate is obtained and polishing with excellent uniformity within a wafer is achieved. The present invention relates to a polishing composition capable of forming a surface and applicable to advanced device forming techniques.

[0003]

2. Description of the Related Art In recent years, so-called high-tech products such as computers have been remarkably advanced, and components used in such products, for example, ULSI, have been increasing in integration and operating speed year by year. Along with this, the design rules of semiconductor devices have been miniaturized year by year, the depth of focus in the device manufacturing process has become shallower, and the flatness required for the pattern formation surface has become stricter.

Further, in order to cope with an increase in wiring resistance due to miniaturization of wiring, the wiring length is shortened by increasing the number of devices. However, steps on the surface of the formed pattern are problematic as obstacles to multilayering. Have been doing.

In performing such miniaturization and multi-layering, it is necessary to flatten a desired surface in order to remove a step during the process. Back and other planarization methods have been used.

However, although these methods can partially planarize, it is difficult to achieve global planarization (complete planarization) required for next-generation devices. 2. Description of the Related Art Flattening (Chemical Mechanical Polishing, hereinafter referred to as "CMP") by mechanochemical polishing combining mechanical or physical polishing and chemical polishing has been studied.

A technical problem in flattening a silicon dioxide film, which is an interlayer insulating film or an insulating film for element isolation, using such a polishing technique is that a surface to be flattened is removed by polishing. It is to improve the productivity by finishing uniformly without excess and deficiency, and by polishing at a high polishing rate.

Conventionally, polishing of a silicon dioxide film used as an interlayer insulating film or an insulating film for element isolation involves the use of fumed silica, water, and a basic compound selected from potassium hydroxide, ammonia and others. Polishing compositions containing have been used. When such a polishing composition is used, the polishing rate can be increased by increasing the amount of the basic compound added.

This is because such a polishing process utilizes a chemical polishing action. With the chemical polishing action, taking the above-mentioned polishing process as an example, the silicon dioxide film is susceptible to chemical erosion due to the effect of a basic compound which is a chemical polishing accelerator, and is susceptible to removal by polishing. It means becoming. That is, in the above-mentioned polishing, the chemical action is increased by increasing the amount of the basic compound added, so that the overall polishing rate is increased.

[0010]

However, as far as the present inventors are aware, the above-mentioned conventional polishing composition usually contains a relatively large amount of a basic compound, and a required level of polishing is required. Although the speed was maintained, the uniformity of the polished surface could not be brought to a sufficiently satisfactory level, and there was still room for improvement. Therefore, a polishing composition that can achieve both a sufficient polishing rate and uniformity of a polished surface has been desired.

[0011]

[Means for Solving the Problems]

[Summary of the Invention] <Summary> The polishing composition of the present invention comprises (1) water, (2) an abrasive, (3) nitric acid, nitrous acid, hydrochloric acid, perchloric acid, chloric acid,
Chlorous acid, hypochlorous acid, boric acid, perboric acid, sulfuric acid, sulfurous acid, persulfuric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, silicic acid,
At least one anion selected from the group consisting of ions of organic acids and their hydrogen acids, or mixtures thereof; (4) a group consisting of ammonium ions, alkali metal ions, and alkaline earth metal ions A polishing composition comprising at least one selected cation, wherein the total amount of the cation of (4) is 0.1.
001 to 0.15 mol / liter.

<Effect> The polishing composition of the present invention can form a polished surface having a high polishing rate and excellent uniformity at the same time.

[Specific description of the invention] <Abrasives> Abrasives suitable for use as an abrasive in the polishing composition of the present invention include silicon dioxide, aluminum oxide, cerium oxide, titanium oxide, silicon nitride, and silicon oxide. It is selected from the group consisting of zirconium and manganese dioxide.

In the present invention, as the silicon dioxide that can be used, there are various types of colloidal silica, fumed silica, and others having different production methods and properties.

Aluminum oxide also includes α-alumina, δ
-Alumina, [theta] -alumina, [kappa] -alumina, and other morphological differences. There is also one called fumed alumina from the manufacturing method.

Cerium oxide includes trivalent and tetravalent cerium oxides in terms of oxidation number, and hexagonal, equiaxed, and face-centered cubic crystals in terms of crystal system.

Titanium oxide includes titanium monoxide, dititanium trioxide, titanium dioxide and others in terms of crystal system. There is also one called fumed titania from the manufacturing method.

Silicon nitride includes α-silicon nitride, β-silicon nitride, amorphous silicon nitride, and other morphologically different ones.

Zirconium oxide includes monoclinic, tetragonal, and amorphous zirconium oxides. Also,
Some are called fumed zirconia from their manufacturing method.

The manganese dioxide includes α-manganese dioxide, β-manganese dioxide, γ-manganese dioxide, δ-manganese dioxide, ε-manganese dioxide, η-manganese dioxide, and the like.

These compositions can be used in the composition of the present invention arbitrarily and in combination as necessary.
When they are combined, the manner of combination and the proportion used are not particularly limited.

The above-mentioned abrasive is for polishing a surface to be polished by mechanical action as abrasive grains. Among these, the particle diameter of silicon dioxide is generally 5 to 500 nm, preferably 10 to 200 nm, as an average particle diameter determined from the specific surface area measured by the BET method. Also, aluminum oxide, zirconium oxide, titanium oxide, silicon nitride,
And the particle diameter of manganese dioxide is generally 10 to 10 in the average particle diameter determined from the specific surface area measured by the BET method
It is 5,000 nm, preferably 50-3,000 nm. Further, the particle size of cerium oxide is an average particle size observed by a scanning electron microscope, and generally ranges from 10 to 5,0.
00 nm, preferably 50 to 3,000 nm.

If the average particle size of these abrasives is larger than the range shown here, there are problems such as large surface roughness of the polished surface and occurrence of scratches. If it is smaller than the range shown here, the polishing rate becomes extremely low, which is not practical.

The content of the abrasive in the polishing composition is less than 40% by weight, preferably 0.1 to 40% by weight, more preferably 1 to 30% by weight, based on the weight of the composition.
It is. If the content of the abrasive is too small, the polishing rate decreases, and if it is too large, uniform dispersion cannot be maintained,
In addition, the viscosity of the composition may be excessively large and handling may be difficult.

<Anion> The polishing composition of the present invention comprises nitric acid, nitrous acid, hydrochloric acid, perchloric acid, chloric acid, chlorous acid, hypochlorous acid, boric acid, perboric acid, sulfuric acid, sulfurous acid, It comprises at least one kind of anion selected from the group consisting of persulfuric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, silicic acid, organic acid, and ions of hydrogen acid thereof, or a mixture thereof. . These anions are generally formed in the polishing composition by dissolving an acid compound which releases the above-mentioned specific anion when dissolved in water, that is, an acid or a salt thereof. In the present invention, since the main solvent is water, a gaseous compound that dissolves in water to release the anion, such as a gaseous hydrochloric acid, a gas of sulfurous acid, and the like, is directly introduced into the water. May be generated.

Any acid compound can be used as long as it does not impair the effects of the present invention. Specifically, (1) nitric acid, nitrous acid, hydrochloric acid, perchloric acid, chloric acid, chlorous acid, hypochlorous acid, boric acid, perboric acid, sulfuric acid,
Sulfurous acid, persulfuric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, silicic acid, or an organic acid such as a carboxylic acid (eg, formic acid,
Acetic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, maleic acid, fumaric acid, glycolic acid, citric acid,
Malic acid, lactic acid, tartaric acid, malonic acid, succinic acid, gluconic acid, propionic acid, butyric acid, or valeric acid), (2)
(1) ammonium salt, sodium salt, potassium salt, lithium salt, beryllium salt, magnesium salt, or calcium salt of the acid of (3), among the acids of (1), a hydrogen salt of an acid having a basicity of 2 or more; No. Among these, nitric acid, hydrochloric acid, boric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, trichloroacetic acid, maleic acid, fumaric acid, glycolic acid, citric acid,
Malic acid, lactic acid, tartaric acid, malonic acid, succinic acid, gluconic acid, propionic acid and the ammonium and potassium salts of these acids, or boric acid, sulfuric acid, phosphoric acid, maleic acid, fumaric acid, glycolic acid, citric acid ,
Particularly preferred are the hydrochlorides consisting of malic acid, lactic acid, tartaric acid, malonic acid or succinic acid and ammonium or potassium ions. These acid compounds can be used together in any ratio.

In the polishing composition of the present invention, the concentration of the specific anion is not limited as long as the effect of the present invention is not impaired.
The total amount of the specific anions is preferably 1/200 to 2 in terms of a molar ratio with respect to the total amount of cations described later, and particularly preferably 1/100 to 1. The polishing rate tends to be increased by increasing the content of a specific anion. However, care must be taken because an excessive increase in the anion may deteriorate the dispersibility of the abrasive.

In the polishing composition of the present invention, it is more preferable to use a water-soluble (easily soluble) acid compound to introduce an anion into the polishing composition from the viewpoint of handleability. Even a hardly soluble compound can be used as long as it can be dissolved in the polishing composition. In other words, the ratio of the total amount of the specific anions to the total amount of the cations is based on the dissolved anions, and it is not necessary to consider the undissolved acid compounds.

<Cation> The polishing composition of the present invention comprises a specific cation. When used in the polishing composition of the present invention, these cations, when used, together with the above-mentioned specific anions or alone, promote the polishing action by a chemical action as a polishing accelerator.

The cation used in the present invention is at least one cation selected from the group consisting of ammonium ion, alkali metal ion and alkaline earth metal ion. In particular, NH ₄ ⁺ , Li ⁺ , N
An ion selected from the group consisting of a ⁺ , K ⁺ , Be ²⁺ , Mg ²⁺ , and Ca ²⁺ (hereinafter referred to as “inorganic alkali ion”) is preferred. Such ions are usually introduced into the polishing composition by dissolving the basic compound that releases the above-mentioned inorganic alkali ions in the polishing composition. The basic compound used here is not particularly limited as long as it does not impair the effects of the present invention.Specifically, potassium hydroxide, ammonium hydroxide, sodium hydroxide, lithium hydroxide, beryllium hydroxide, At least one compound selected from the group consisting of magnesium hydroxide and calcium hydroxide is exemplified. These basic compounds can be used together in any ratio. In addition, as for the above-mentioned basic compound, it is preferable to use a high-purity metal compound having very little metal ions other than the above-mentioned inorganic alkali ions, because impurity metal ions can be reduced in the polishing composition.

The content of the cation in the polishing composition of the present invention is 0.001 to 0.001 to the total amount of the polishing composition.
0.15 mol / l, preferably 0.005 to 0.
1 mol / liter, more preferably 0.01 to 0.0
75 mol / l. Increasing the content of the inorganic alkali ions tends to increase the polishing rate, but if it is too high, the uniformity of the polished surface tends to deteriorate.
Further, attention must be paid to the extent that the degree of improvement with respect to the polishing rate or the like is reduced, which may cause economical disadvantages.

<Polishing Composition> The polishing composition of the present invention is generally prepared by mixing the above-mentioned abrasive in water at a desired content,
It is prepared by dispersing and dissolving a predetermined amount of the compound that releases the specific anion and the compound that releases the inorganic alkali ion. The method of dispersing or dissolving these components in water is arbitrary. For example, the components are stirred by a blade-type stirrer or dispersed by ultrasonic dispersion. In addition, the order of mixing these components is arbitrary,
Either the dispersion of the abrasive or the dissolution of the acid compound or the basic compound may be performed first, or both may be performed simultaneously.

In preparing the polishing composition of the present invention, various types of polishing compositions may be used depending on the purpose of maintaining and stabilizing the quality of the product, the type of the workpiece, the processing conditions, and other polishing processing needs. May be further added.

That is, preferable examples of the additive to be further added include the following. (A) celluloses, such as cellulose, carboxymethylcellulose, hydroxyethylcellulose, and others; (B) water-soluble alcohols, such as ethanol, propanol, ethylene glycol, and others; (C) surfactants, such as sodium alkylbenzene sulfonate; Formalin condensates of naphthalenesulfonic acid, and others, (d) organic polyanionic substances such as ligninsulfonate, polyacrylate, and others, (e) water-soluble polymers (emulsifiers) such as polyvinyl alcohol, and Others, (f) fungicides such as sodium alginate, and others.

Further, the polishing composition of the present invention includes, in addition to the abrasive, the acid compound, and the basic compound contained therein, those described above as the abrasive, the acid compound, and the basic compound. Other things to do,
It can also be used as a further additive for purposes other than the use of the abrasive or polishing accelerator, for example to prevent settling of the abrasive.

The polishing composition of the present invention usually has a pH of 4 to 10 due to the addition of the above-mentioned main component.
The pH of the polishing composition fluctuates due to the addition of various auxiliary additives.
It is preferably from 10 to 10. Therefore, when the pH of the polishing composition deviates from the range of 4 to 10, it is preferable to adjust the pH by adding an acid or an alkali.
Even when the pH is within this range, it may be preferable to further adjust the pH for other reasons, for example, storage stability of the polishing composition, physical properties of the object to be polished, and the like.

The polishing composition of the present invention comprises a semiconductor,
It can be applied to any substrate such as a photomask, various memory hard disk bases and various industrial products such as synthetic resin or its members, but is particularly used for surface flattening of device wafers in the semiconductor industry and the like. Is preferred.

The polishing composition of the present invention can be prepared as a stock solution having a relatively high concentration, stored or transported, and diluted at the time of actual polishing. The above-mentioned preferred concentration range is described as an actual polishing process, and it goes without saying that when such a method of use is taken, a solution having a higher concentration is obtained in a state of being stored or transported. . In addition, from the viewpoint of handleability, it is preferable to manufacture in such a concentrated form. The above-mentioned concentrations and the like for the polishing composition are not the concentrations at the time of production but describe the concentrations at the time of use.

Hereinafter, the polishing composition of the present invention will be specifically described using examples.

Note that the present invention is not limited to the configurations of the examples described below as long as the gist is not exceeded.

[0041]

DETAILED DESCRIPTION OF THE INVENTION <Contents and Preparation of Polishing Composition> First, fumed silica (primary particle diameter 50 nm, secondary particle diameter 2
00 nm) was dispersed in water using a stirrer to prepare a slurry having an abrasive concentration of 15% by weight. Next, acid compounds and ammonia (basic compounds) were added to the slurry so as to have the concentrations or contents described in Table 1, to prepare samples of Examples 1 to 8 and Comparative Examples 1 and 2.

Here, the acid concentration is the molar concentration of the acid compound dissolved in the polishing composition, and the ammonia content is that dissolved in the polishing composition. The total amount of ammonia is expressed in molar concentration.

<Polishing Test> Next, polishing tests were performed on the samples of Examples 1 to 8 and Comparative Examples 1 and 2. As a workpiece, a substrate of a 6-inch silicon wafer (outer diameter: about 150 mm) on which a silicon dioxide film was formed by a CVD method was used, and the surface of the silicon dioxide film with the film was polished.

Polishing was performed using a single-side polishing machine (platen diameter: 570 mm). Non-woven fabric pad (Ro
A polishing pad in which a foamed urethane pad (IC-1000 manufactured by Rodel (USA)) was bonded onto Dela (USA) (Suba400) was loaded and polished for 3 minutes by mounting a wafer with a silicon dioxide film.

The polishing conditions were as follows: processing pressure 490 g / cm ² ,
Surface plate rotation speed 35rpm, polishing composition supply amount 150cc
/ Min, and the wafer rotation speed was set to 70 rpm.

After the polishing, the wafer is sequentially washed and dried, and then the thickness of the wafer is reduced, that is, the stock removal by polishing is reduced to 49.
The point was measured, the average was divided by the polishing time, and the polishing rate was determined for each test.

From the 49-point allowance determined above,
NU, which is an evaluation standard for the uniformity of the polished surface, was determined by the following equation. NU (%) = {R. (max) -R. (Min)} / {R. (ave) ×
2｝ × 100 In the above equation, R. (max) represents the maximum allowance, R. (min) represents the minimum allowance, and R. (ave) represents the average allowance.

As is apparent from this equation, NU is an index representing unevenness of the wafer surface due to variation in film thickness reduction occurring during polishing, that is, non-uniformity of allowance. The larger the NU value, the greater the variation in the stock removal by polishing, and conversely, the smaller the NU value, the smaller the variation in the stock removal by polishing.

Table 1 Types of ammonium acid Acid compound Polishing rate NU Content Concentration [mol / l] [mol / l] [nm / min] [%] Example 1 0.0347 Nitric acid 0.0086 147 5.8 Example 2 0.0347 Hydrochloric acid 0.0086 151 5.6 Example 3 0.0347 Sulfuric acid 0.0086 156 5.2 Example 4 0.0347 Phosphoric acid 0.0086 155 5.3 Example 5 0.0347 Formic acid 0.0086 153 5.6 Example 6 0.0347 Acetic acid 0.0086 151 5.8 Example 7 0.0347 Maleic acid 0.0086 157 5.1 Example 8 0.0347 glycol Acid 0.0086 154 6.5 Comparative Example 1 0.3071--143 14.7 Comparative Example 2 0.0347--135 6.6

From the results shown in Table 1, the conventional polishing composition has a significantly lower polishing rate or a significantly lower NU than the polishing composition of the present invention. It can be seen that the polishing composition has both excellent polishing rate and excellent uniformity of the polished surface.

Although not shown in Table 1 above, the polished surfaces used in these tests were visually evaluated. In both the Examples and Comparative Examples, scratches and other surface defects were observed. I was not issued.

[0052]

As described above, the polishing composition of the present invention can form a polished surface having a high polishing rate and excellent uniformity.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 21/304 321 H01L 21/304 321P // G11B 5/84 G11B 5/84 A

Claims (7)

[Claims] (1) water, (2) abrasive, (3) nitric acid, nitrous acid, hydrochloric acid, perchloric acid, chloric acid, chlorous acid, hypochlorous acid, boric acid, perboric acid, sulfuric acid At least one anion selected from the group consisting of: sulfurous acid, persulfuric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, silicic acid, organic acid, and ions of hydrogen acid thereof, or a mixture thereof. ,
(4) At least one type of cation selected from the group consisting of ammonium ions, alkali metal ions, and alkaline earth metal ions. A polishing composition comprising: (4) wherein the total amount of cations in (4) is 0.001 to 0.
A polishing composition characterized by being 15 mol / l. 2. The polishing composition according to claim 1, wherein the content of the abrasive is less than 40% by weight based on the weight of the polishing composition. 3. The abrasive according to claim 1, wherein the abrasive is at least one abrasive selected from the group consisting of silicon dioxide, aluminum oxide, cerium oxide, titanium oxide, silicon nitride, zirconium oxide, and manganese dioxide.
The polishing composition according to any one of the above. 4. The method according to claim 1, wherein the cation is NH ₄ ⁺ , Li ⁺ , Na ⁺ ,
The cation is at least one cation selected from the group consisting of K ⁺ , Be ²⁺ , Mg ²⁺ , and Ca ²⁺ .
4. The polishing composition according to any one of 3. 5. The polishing composition according to claim 1, wherein the total amount of the cations is 0.005 to 0.1 mol / L. 6. The total amount of cations is 0.01 to 0.075.
The polishing composition according to any one of claims 1 to 4, wherein the polishing composition has a mole / liter. 7. The polishing composition according to claim 1, wherein the total amount of said anions is 1/200 to 2 in molar ratio with respect to said cations.