CN101451046B - Polishing composition for silicon wafer polishing - Google Patents

Abstract

The invention discloses a silicon wafer polishing composition in the field of chemical mechanical polishing (CMP). The polishing composition comprises silica, a polishing interface control agent, a surfactant, a chelating agent, an alkaline compound and water, wherein the particle diameter of the silica in the polishing composition is between 1 and 200 nm; the content of the silica is between 0.05 and 50 weight percent; the polishing interface control agent is polyhydroxy cellulose ether; the content of the polishing interface control agent is between 0.001 and 10 weight percent; the content of the surfactant is between 0.001 and 1 weight percent; the content of the chelating agent is between 0.001 and 1 weight percent; the content of the alkaline compound is between 0.001 and 10 weight percent; the balance being water; and the PH value is between 8.5 and 12. The polishing interface control agent can control a polishing interface between abrasive particles and a polishing object in the chemical mechanical polishing process in order that the surface of the polished silicon wafer is more perfect. The polishing composition is in particular suitable for polishing the silicon wafer and has the advantages of rapid polishing speed, little surface defect and high planeness; and the polished silicon wafer has few metal ion contaminants and is easy to clean.

Description

A polishing composition for silicon wafer polishing

technical field

The invention relates to a polishing composition for silicon wafer polishing in the field of chemical mechanical polishing (CMP).

Background technique

Semiconductor materials, mainly silicon materials, are the most important basic functional materials in the electronic information industry, and occupy a very important position in the national economy and military industry. More than 95% of the world's semiconductor devices are made of silicon materials, and 85% of integrated circuits are also made of silicon materials. At present, IC technology has entered the era of nanoelectronics with a line width of less than 0.1 μm, and the requirements for the surface processing quality of silicon single crystal polished wafers are getting higher and higher. Traditional polishing fluids can no longer meet the requirements of silicon single wafer polishing. In order to ensure higher machining accuracy such as warpage, local surface flatness, and surface roughness of silicon polishing wafers, it is necessary to develop new polishing fluids and polishing processes. Obtaining silicon wafers with higher surface processing precision is an important link in the manufacture of integrated circuits, which is directly related to the pass rate of integrated circuits.

Pure chemical polishing has slow polishing rate, high surface precision, low damage, and good integrity, but it cannot correct the surface accuracy, and the polishing consistency is poor; pure mechanical polishing has good consistency and high surface flatness. The polishing rate is high, but the damage layer is deep and the surface accuracy is low; chemical mechanical polishing can not only obtain a more perfect surface, but also obtain a high polishing rate, which is the only way to achieve global planarization. A traditional CMP system consists of the following three parts: a rotating silicon wafer holding device, a workbench carrying a polishing pad, and a polishing liquid (slurry) supply system. During polishing, the rotating workpiece is applied with a certain pressure on the polishing pad that rotates with the worktable. The polishing liquid flows between the workpiece and the polishing pad, and a chemical reaction occurs on the surface of the workpiece. The chemical reactants formed on the surface of the workpiece are formed by the abrasive. Mechanical friction is removed. In the alternating process of chemical film formation and mechanical film removal, a very thin layer of material is removed from the surface of the workpiece through the joint action of chemistry and machinery, and ultra-precision surface processing is finally realized. Therefore, in order to achieve high-efficiency and high-quality polishing, it is necessary to achieve a good match between the chemical action process and the mechanical action process.

In order to achieve the goals of fast polishing rate, less surface defects and high flatness of silicon wafer polishing liquid, various methods have been tried at home and abroad, and some progress has been made.

People such as Trednnick disclose a kind of polishing liquid (patent US3715842) that is used for silicon essence polishing, and it comprises the silicon dioxide particle that size is not greater than 100nm in water, adds the ammonia of 0.05wt% or greater concentration, adds 0.05～2.5wt % hydroxymethyl cellulose (HMC), hydroxyethyl cellulose (HEC) and hydroxypropyl cellulose (HPC); Lu Xuanxiu et al. disclose a composition (patent WO2004053968) for silica polishing, which contains 2-10 wt% of colloidal silicon dioxide with a particle size range of 30-80nm, 0.5-1.5 wt% of ammonia, 0.2-1 wt% of hydroxycellulose, and 0.03-0.5 wt% of polyoxyethylene alkylamine ether. These methods all reduce the surface defects of silicon wafers, but the polishing removal rate is not high, so they are only suitable for silicon polishing.

Yamada Xiuping and others disclosed a rough polishing composition for silicon (patents JP2003313838 and JP2001110760), which disclosed a polishing solution containing EO-PO block copolymers, which improved the surface quality of silicon wafers, but provided less information. The specific mechanism of action of the added block copolymers is not stated.

People such as Sasaki disclose a kind of silicon wafer polishing composition (patent EP0371147B1, JP09324174) containing the silica sol modified by silane coupling agent; WO2004042812); Patents US5876490 and US3922393 adopt ceria-coated and alumina-coated silica particles; patent US4664679 adopts a modification method for reducing silanol groups on the surface of colloidal silica. These treatments have achieved a certain effect on the control of defects, but for the new generation of single crystal silicon polishing fluid with higher requirements, the above methods still have certain limitations.

Contents of the invention

The invention overcomes the problems of many surface defects, low removal rate, many metal residues and difficult cleaning which are easily caused by the traditional silicon wafer polishing liquid in the polishing process. The invention discloses a silicon wafer polishing composition with fast polishing rate, less surface defects, high flatness, less metal ion pollutants on the polished silicon wafer and easy cleaning.

In order to achieve the above object, the present invention adopts the polyhydroxy cellulose ether which can control the polishing interface, prevents the generation of the polishing interface which is prone to polishing defects, and improves the action efficiency of the polishing abrasive grains. In order to further improve the performance of the polishing composition during the polishing process, other substances are added to the polishing composition, so that the abrasive in the polishing composition can maintain a good dispersion state and have good stability.

The polishing composition for silicon wafer polishing, its component and proportioning are:

Silica particles 0.05～50wt%

Basic compound 0.001～10wt%

Chelating agent 0.001～1wt%

Surfactant 0.001%～1wt%

Polishing interface control agent 0.001%～10wt%

Deionized water balance

The silicon dioxide is colloidal silicon dioxide, and the particle size of the silicon dioxide particles is 1-500 nm.

The basic compound is potassium hydroxide, sodium hydroxide, ammonium carbonate, ammonium bicarbonate, potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate, tetramethylammonium hydroxide, ammonia, methylamine, dimethyl Baseamine, trimethylamine, ethylamine, diethylamine, triethylamine, isopropanolamine, aminopropanol, tetraethylamine, ethanolamine, diethyltriamine, triethylenetetramine, One or more of hydroxyethylethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, anhydrous piperazine, and hexahydrate piperazine.

The chelating agent is ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, ethylenediaminetetraethylenephosphonic acid, ethylenediaminetetramethylene Phosphonic acid, diethylenetriaminepentaethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, triethylenetetraminehexaethylenephosphonic acid, propylenediaminetetraethylenephosphonic acid, and propylenediaminetetraethylenephosphonic acid Methylene phosphonic acid, and one or more of their ammonium salts, potassium salts, sodium salts and lithium salts.

The surfactant is one or more of nonionic surfactants, anionic surfactants or cationic surfactants.

The polishing interface control agent is polyhydroxy cellulose ether, and its structural formula is:

Wherein, n is an integer ≥ 2.

The nonionic surfactant is polydimethylsiloxane, dimethylpolysiloxane polyether copolymer, polyoxyethylene (9) lauryl ether, fatty alcohol polyoxyethylene ether, nonylphenol polyoxygen One or more of vinyl ether, octylphenol polyoxyethylene ether, polyoxypropylene polyoxyethylene block copolymer, polyacrylamide; anionic surfactants are sodium dodecylbenzenesulfonate, dodecane One of sodium sulfonate, sodium α-olefin sulfonate, sodium diisooctyl sulfonate, fatty alcohol (10) polyoxyethylene, sodium ether carboxylate, sodium fatty alcohol polyoxyethylene ether sulfate or Several; cationic surfactants are Tetradecyldimethylbenzylammonium Chloride, Lauryltrimethylammonium Chloride, Guar Hydroxypropyltrimethylammonium Chloride, Dodecyl Bromide One or more of trimethyl ammonium bromide and dodecyl dimethyl benzyl ammonium bromide.

The polyhydroxy cellulose ether is dihydroxypropyl cellulose ether, and R is one of the following groups in its structural formula:

R is

The molecular weight of the dihydroxypropyl cellulose ether is 300,000 to 3,000,000.

The specific steps of the polishing composition preparation method for silicon wafer polishing are as follows:

1) Dispersing the colloidal silicon dioxide in water with a stirrer to obtain a slurry with an abrasive concentration of 0.05 to 50 wt %;

2) Add a polishing interface control agent, accounting for 0.001% to 10% by weight of the polishing composition, fully mix the polishing interface control agent and colloidal silicon dioxide in the agitator, and control the polishing interface between the colloidal silicon dioxide and the polishing composition The mass ratio of the agent is 10-500;

3) adding surfactants and chelating agents in sequence, respectively accounting for 0.001% to 1% by weight and 0.001% to 1% by weight of the polishing composition, to ensure that the polishing composition system remains stable;

4) adding a basic compound, accounting for 0.001-10 wt% of the polishing composition, and adjusting the pH of the polishing composition to 8.5-12;

5) Filter the polishing composition with a Shishi core with a pore size of 0.5 μm to remove large particles of impurities in the polishing composition, that is, obtain the polishing composition of the present invention.

Compared with the prior art, the present invention has the following advantages:

1) The polishing composition of the present invention contains a polishing interface control agent, which can strongly inhibit the surface defects caused by scratches and gel deposition of polishing abrasives in the polishing composition;

2) The polishing composition of the present invention realizes good matching between chemical action and mechanical action in the CMP process, and realizes high-efficiency and high-quality polishing.

3) The polishing composition of the present invention further reduces the metal pollution on the surface of the silicon chip and the deposition of particles in the air, and improves the cleaning efficiency after polishing.

4) The raw materials used in the polishing composition of the present invention are readily available and easy to carry out large-scale industrial production.

Description of drawings

Fig. 1 is an atomic force microscope (AFM) photo of a polished silicon wafer when the polishing control agent of the polishing composition of the present invention matches other components (Example 14).

Fig. 2 is an AFM photograph of a polished silicon wafer when the polishing composition of the present invention does not contain a polishing control agent (Example 1).

3 is an AFM photo of a polished silicon wafer when the polishing control agent in the polishing composition of the present invention is poorly matched with other components (Example 9).

Detailed ways

The present invention will be further illustrated by the following examples and comparative examples (without adding the polishing surface control agent in the composition of the present invention), which certainly should not be construed as limiting the scope of the present invention in any way.

(1) Preparation Examples

The polishing composition is prepared. According to the specific polishing implementation needs, each embodiment is configured with 6000g of polishing composition for polishing experiments, wherein the selected colloidal silica is purchased by itself and is a product of Guangzhou People's Chemical Factory, with a particle size of 40nm. Silicon oxide content 30%:

Example 1

Disperse 400g of colloidal silicon dioxide with a silicon dioxide content of 30% in 5464.4g of deionized water with a stirrer, add 120g of an aqueous solution containing 2% of dihydroxypropyl cellulose ether as a polishing interface control agent, and place in the stirrer Make the polishing interface control agent and colloidal silicon dioxide fully mixed; then add surfactant DC-193 (dimethylpolysiloxane polyether copolymer) 2.4g, chelating agent EDTA (ethylenediaminetetraacetic acid) 1.2g Add 12 g of basic compound TETA (triethylenetetramine), and finally filter the polishing composition with a filter element with a pore size of 0.5 μm, as shown in Table 1.

Embodiment 2～3

The preparation process was the same as in Example 1, and the amounts of the 2% aqueous solution of the polishing interface control agent dihydroxypropyl cellulose ether added were 180 g and 240 g, as shown in Table 1.

Example 4

The preparation process is the same as in Example 1, dispersing 400 g of colloidal silicon dioxide with a silicon dioxide content of 30% in 5270.6 g of deionized water with a stirrer, and adding 2% dihydroxypropyl cellulose ether containing polishing interface control agent 300g of the aqueous solution, the polishing interface control agent and the colloidal silicon dioxide are fully mixed in the stirrer; then add the surfactant AEO-9 (polyoxyethylene (9) lauryl ether) 3.6g, the chelating agent TTHP (triethyl ether) successively Tetraamine hexaethylene phosphonic acid) 1.8g; Add two basic compounds DETA (triethylenetetramine) and PIZ (piperazine anhydrous), respectively 12g and 6g, and finally use a filter element with a pore size of 0.5 μm to The polishing compositions were filtered as shown in Table 1.

Example 5

Disperse 600 g of colloidal silicon dioxide with a silicon dioxide content of 30% in 5077.8 g of deionized water with a stirrer, add 300 g of an aqueous solution containing 2% of dihydroxypropyl cellulose ether as a polishing interface control agent, and place in the stirrer Fully mix the polishing interface control agent with colloidal silicon dioxide; then add 1.2 g of surfactant AEO-9 (polyoxyethylene (9) lauryl ether) and chelating agent EDTEP (ethylenediaminetetraethylenephosphonic acid) in sequence 2.4g; add two basic compounds PHA (potassium hydroxide) and DEA (diethylamine), respectively 12g and 6g, and finally filter the polishing composition with a filter element with a pore size of 0.5 μm, as shown in Table 1 .

Embodiment 6-9

The preparation method is the same as in Example 5, as shown in Table 1.

The added abrasive grains are all 600g of colloidal silicon dioxide with a silicon dioxide content of 30%; the amount of the added polishing interface control agent is 600g of an aqueous solution containing 2% of dihydroxypropyl cellulose ether;

Wherein embodiment 6 adds surfactant DBS (sodium dodecylbenzenesulfonate) 2.4g, adds chelating agent DTPA (diethylenetriaminepentaacetic acid) 1.8g, adds basic compound AEEA (hydroxyethylethylenediamine) ) 12g.

Add surfactant DBS (sodium dodecylbenzenesulfonate) 2.4g in embodiment 7, add chelating agent DTPA (diethylenetriaminepentaacetic acid) 1.8g, add two kinds of basic compounds AEEA (hydroxyethyl ethylene diacetate) 12 g each of amine) and PIZ (piperazine anhydrous).

Add surfactant OP-10 (octylphenol polyoxyethylene ether) 1.2g in embodiment 8, AEO-9 (polyoxyethylene (9) lauryl ether) 0.6g, add chelating agent PDTEP (propylene diamine tetraethylene ethylphosphonic acid) 1.8 g, and 12 g of the basic compound AEEA (hydroxyethylethylenediamine) was added.

Add surfactant OP-10 (octylphenol polyoxyethylene ether) 1.2g in embodiment 9, AEO-9 (polyoxyethylene (9) lauryl ether) 0.6g, add chelating agent PDTEP (propylene diamine tetraethylene Ethylphosphonic acid) 1.8g, add basic compound AEEA (hydroxyethylethylenediamine) 12g, DEA (diethylamine) 18g.

Comparative example 1-4

In the comparative example, except that the polishing interface control agent described in the present invention is not added, other configuration comparative examples are the same as the embodiment configuration process, wherein comparative example 1 and embodiment 1; comparative example 2 and embodiment 4; comparative example 3 and embodiment 4; Embodiment 5; Comparative Example 4 corresponds to Embodiment 8, as shown in Table 1.

(two) test embodiment

The polishing composition after configuration is used for polishing experiment, and polishing experiment parameter is as follows:

Polishing machine: single-sided polishing machine, equipped with 4 polishing heads, each polishing head can polish 4 silicon wafers;

Polishing pressure: 32kPa;

Polishing turntable speed: 90 rpm;

Polishing head speed: 100 rpm;

Specifications of polished silicon single wafer: P type <100>, diameter 100mm, resistivity: 0.1～100.Ω·cm;

Polishing time: 20min;

Polishing pad: polyurethane foam curing polishing pad, Rodel MH Pad S-15;

Polishing fluid flow rate: 230ml/min;

Polishing temperature: 20°C

Polishing rate: The polishing removal rate is calculated by the change of the thickness of the center part of the silicon wafer before and after polishing. It is the average value of the difference in the center thickness of the four silicon wafers. It can be measured by a micrometer. The polishing rate is the ratio of the polishing removal rate to the polishing time .

Surface quality inspection of polished silicon wafers: use AFM to detect the surface roughness of polished silicon wafers. The AFM used in the experiment is Vecco 3100, the probe radius is 10nm, the vertical resolution is 0.01nm, and the scanning frequency is 1.5Hz. In order to avoid the influence of the attached impurities on the surface of the silicon wafers on the experimental results, the silicon wafers were ultrasonically cleaned in acetone, absolute ethanol, and deionized water before the experiment.

As can be seen from the polishing experimental results of the examples and comparative examples in Table 1, compared with conventional polishing compositions, the polishing composition of the present invention has a high polishing removal rate due to containing a polishing interface control agent (DHPC) and simultaneously extremely Greatly improved the surface quality of the polished silicon wafer. By adjusting the content of the polishing surface control agent in the polishing composition, and at the same time adjusting the type and content of other components in the polishing composition, the performance of the polishing interface control agent can play its unique role.

As can be seen from the foregoing examples, the content of each component in the optimum polishing composition under the polishing process conditions of the present invention is: the polishing interface control content is 0.1%, containing 0.06% of surfactant AEO-9, containing alkaline compound DETA 0.3%, PIZ 0.1%, and chelating agent TTHP 0.03%, the surface roughness of the silicon wafer polished by the polishing composition is as low as 0.24nm, and the removal rate reaches 1.35μm/min.

The above examples fully demonstrate that the polishing composition of the present invention is a polishing material for CMP with excellent performance, especially suitable for polishing silicon wafers.

Claims (10)

1. polishing composition that is used for silicon wafer polishing, its component and proportioning are:

The agent of said polishing Interface Control is the polyhydroxy cellulose ether.

2. the polishing composition that is used for silicon wafer polishing according to claim 1 is characterized in that, said silicon dioxide is cataloid, and the silica dioxide granule particle diameter is 1～500nm.

3. the polishing composition that is used for silicon wafer polishing according to claim 1; It is characterized in that said alkali compounds is one or more in potassium hydroxide, NaOH, ammonium carbonate, carbonic hydroammonium, saleratus, potash, sodium acid carbonate, sodium carbonate, TMAH, ammonia, dimethyl amine, Trimethylamine, ethylamine, diethylamide, triethylamine, aminopropanol, tetraethyl amine, monoethanolamine, diethyl triamine, triethyl group tetramine, AEEA, hexamethylene diamine, diethylenetriamines, trien, Piperazine anhydrous, the anthalazine.

4. the polishing composition that is used for silicon wafer polishing according to claim 3 is characterized in that, said aminopropanol is an isopropanolamine.

5. the polishing composition that is used for silicon wafer polishing according to claim 1; It is characterized in that; Said chelating agent is ethylenediamine tetra-acetic acid, trimethylen-edinitrilo-tetraacetic acid, diethyl pentetic acid, triethyl group tetramine six acetate, ethylenediamine tetraacetic ethylidene phosphonic acids, ethylenediamine tetramethylene phosphonic acid, Diethylenetriamine five ethylidene phosphonic acids, Diethylenetriamine pentamethylene phosphonic acids, three second tetramines, six ethylidene phosphonic acids, propane diamine four ethylidene phosphonic acids and propane diamine tetramethylene phosphonic acid, and in their ammonium salt, sylvite, sodium salt and the lithium salts one or more.

6. the polishing composition that is used for silicon wafer polishing according to claim 1 is characterized in that, said surfactant is one or more in non-ionic surface active agent, anion surfactant or the cationic surfactant.

7. the polishing composition that is used for silicon wafer polishing according to claim 1 is characterized in that, said polyhydroxy cellulose ether is the dihydroxypropyl cellulose ether, and structural formula is:

Wherein, n is >=2 integer;

R is a kind of in the following group in the structural formula:

R is

8. the polishing composition that is used for silicon wafer polishing according to claim 6, said non-ionic surface active agent are one or more in dimethyl silicone polymer, dimethyl polysiloxane copolyether, polyoxyethylene (9) lauryl alcohol, AEO, NPE, OPEO, polyoxyethylene polyoxypropylene block copolymer, the polyacrylamide; Anion surfactant is neopelex, dodecyl sodium sulfate, one or more in alpha-olefin sodium sulfonate, succinate sodium 2-ethylhexyl, fatty alcohol (10) polyoxyethylene, ether carboxylic acid sodium, the sodium sulfate of polyethenoxy ether of fatty alcohol; Cationic surfactant is one or more in myristyl dimethyl benzyl ammonium chloride, DTAC, guar hydroxypropyl trimonium chloride, bromination dodecyl trimethyl ammonium, the bromination dodecyl dimethyl hexadecyldimethyl benzyl ammonium.

9. the polishing composition that is used for silicon wafer polishing according to claim 7 is characterized in that, said dihydroxypropyl cellulose ether amount is 30～3,000,000.

10. a preparation method who is used for the polishing composition of silicon wafer polishing is characterized in that, said method concrete steps do,

1) cataloid is scattered in it in deionized water with blender, obtains the slurries that abrasive concentration is 0.05～50wt%;

2) add the agent of polishing Interface Control; Account for 0.001%～10wt% of polishing composition; The agent of polishing Interface Control is fully mixed with cataloid; And the mass ratio with the agent of polishing Interface Control of cataloid is 10～500 in the polishing composition, and the agent of said polishing Interface Control is the polyhydroxy cellulose ether;

3) add surfactant, chelating agent successively, account for the 0.001%～1wt% and the 0.001～1wt% of polishing composition respectively, keep stable to guarantee the polishing composition system;

4) add alkali compounds, account for 0.001～10wt% of polishing composition, and polishing composition pH is adjusted to 8.5～12;

5) using the aperture is that the filter core of 0.5 μ m filters polishing composition, to remove the large granular impurity in the polishing composition, promptly obtains polishing composition of the present invention.

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