TWI652320B - Wetting agent for semiconductor substrate and polishing composition - Google Patents

Abstract

The present invention relates to a wetting agent for a semiconductor substrate containing hydroxyethylcellulose and water, wherein the hydroxyethylcellulose has a radius of inertia of 56 nm or more and 255 nm or less, and a contact angle of 10 or more and 32 or less.

Description

Wetting agent for semiconductor substrate and polishing composition

[Reciprocal reference to related applications]

The priority of the Japanese Patent Application No. 2013-267255 is hereby incorporated by reference in its entirety in its entirety in its entirety in the entirety in

The present invention relates to a wetting agent for a semiconductor substrate and a polishing composition.

In recent years, with the integration of integrated circuits and the like, the miniaturization of semiconductor devices has been progressing, and as a result, semiconductor substrates (hereinafter also simply referred to as wafers) such as semiconductor wafers (hereinafter also referred to simply as substrates) are required to be high. Flatness, in addition, requires a higher level of surface wettability and reduced surface defects.

In order to improve the wettability of the wafer surface and reduce surface defects, it is considered to treat the surface of the wafer by, for example, using an aqueous solution of a water-soluble polymer as a component for improving wettability.

It is known that a wet film formed of a water-soluble polymer is applied to a surface of a wafer by treating the wafer with an aqueous solution containing a water-soluble polymer to improve wettability.

Such a solution which can improve wettability is described, for example, in Patent Document 1.

Patent Document 1 describes a polishing wetting agent and a polishing composition containing hydroxyethyl cellulose as a water-soluble polymer.

A water-soluble polymer such as hydroxyethyl cellulose is a component which improves wettability as described above, but on the other hand, it is easy to produce an insoluble substance in an aqueous solution, and the insoluble substance adheres to the processed wafer. The surface may be a cause of surface defects such as haze value of the wafer surface or an increase in LPD (Light Point Defects) value.

Patent Document 1 describes that an insoluble substance which is a cause of surface defects is easily removed by filtration by using hydroxyethyl cellulose having a specific viscosity.

However, the wetting agent or the polishing composition described in Patent Document 1 does not inhibit the generation of insoluble substances in the solution. Therefore, when the filtration is insufficient, the surface defects of the wafer after polishing cannot be suppressed. Further, since the insoluble matter which is fine to the extent that it cannot be filtered can not be removed, it is impossible to prevent the extremely fine insoluble matter from adhering to the surface of the wafer. Therefore, there is a problem that the reduction in surface defects is insufficient.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2012-89862

Therefore, the present invention has been made in view of the above problems as described above, and it is an object of the invention to provide a wetting agent for a semiconductor substrate and a polishing composition which can sufficiently reduce the surface defects of a substrate while sufficiently improving the wettability of the surface of the semiconductor substrate.

The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that the use of hydroxyethyl cellulose having a specific inertia radius and contact angle can improve wettability and reduce surface defects, thereby completing the present invention.

The wetting agent for a semiconductor substrate of the present invention contains hydroxyethylcellulose and water, and the hydroxyethylcellulose has a radius of inertia of 56 nm or more and 255 nm or less, and a contact angle of 10 or more and 32 or less.

In the present invention, the pH of the wetting agent for a semiconductor substrate may be 9.0 or more and 11.0 or less.

The polishing composition of the present invention contains hydroxyethylcellulose, water, and abrasive grains, and the hydroxyethylcellulose has a radius of inertia of 56 nm or more and 255 nm or less, and a contact angle of 10 or more and 32 or less.

In the present invention, the polishing composition may have a pH of 9.0 or more and 11.0 or less.

Hereinafter, the wetting agent for semiconductor substrate and the polishing composition of the present invention will be described.

The wetting agent for a semiconductor substrate of the present embodiment contains hydroxyethylcellulose and water, and the hydroxyethylcellulose has a radius of inertia of 56 nm or more and 255 nm or less, and a contact angle of 10 or more and 32 or less.

Hydroxyethyl cellulose is a hydrophilic polymer and is easily made into an aqueous solution by mixing with water. By contacting the aqueous solution of the hydroxyethylcellulose with the surface of the semiconductor substrate such as a ruthenium wafer, hydrophilicity can be imparted to the surface to improve wettability.

The hydroxyethylcellulose contained in the wetting agent of the present embodiment has a radius of inertia of 56 nm or more and 255 nm or less (560 Å or more and 2550 Å or less), preferably 56 nm or more and 207 nm or less (560 Å or more and 2070 Å or less). ).

When the inertia radius of the hydroxyethyl cellulose is in the above range, the wettability can be improved while suppressing the generation of the insoluble matter in the aqueous solution.

The radius of inertia of the hydroxyethyl cellulose in the present embodiment means the radius of inertia in water.

The radius of inertia refers to the radius of inertia measured by the static light scattering method, and specifically refers to a value measured by the measurement method shown in the following examples.

The contact angle of the hydroxyethylcellulose contained in the wetting agent of the present embodiment is 10° or more and 32° or less, preferably 15° or more and 29° or less.

When the contact angle of hydroxyethylcellulose is in the above range, the wettability can be improved and the generation of the insoluble matter in the aqueous solution can be suppressed.

The contact angle of hydroxyethylcellulose in the present embodiment means a tetraethyl orthosilicate having a surface roughness (Ra) of 10 angstroms (1 nm) in a 0.3% by mass aqueous solution of hydroxyethylcellulose ( The contact angle of the wafer surface produced by TEOS) specifically refers to a value measured by the measurement method shown in the following examples.

The hydroxyethyl cellulose in the present embodiment is preferably used in an absolute molecular weight of, for example, 300,000 or more, preferably 300,000 or more and 4,000,000 or less, more preferably 3,000,000 or more and 3.6 million or less.

When the absolute molecular weight is in the above range, the generation of the insoluble matter in the aqueous solution can be further suppressed.

The absolute molecular weight of the hydroxyethylcellulose in the present embodiment is the absolute molecular weight measured by the light scattering method, and specifically means a value measured by the measurement method shown in the following examples.

The content of the hydroxyethyl cellulose in the wetting agent for a semiconductor substrate is not particularly limited, and is, for example, 0.1 ppm or more and 20,000 ppm or less, preferably 10 ppm or more and 10000 ppm or less.

When the content of the hydroxyethylcellulose is in the above range, the insolubility of the substrate surface can be sufficiently improved while suppressing the generation of the insoluble matter.

The pH of the wetting agent of the present embodiment may be 9.0 or more and 11 or less, and preferably the pH is 9.5 or more and 10.5 or less.

When the pH of the wetting agent is in the above range, the generation of insoluble matter can be more effectively suppressed.

In order to adjust the pH to the above range, the wetting agent of the present embodiment may also contain There are known pH adjusters.

Examples of the pH adjuster include ammonia, a tetrabasic ammonium hydroxide salt such as tetramethylammonium hydroxide, tetraethylammonium hydroxide or tetrabutylammonium hydroxide.

Among them, it is preferable that ammonia is less likely to cause metal impurities to be generated on the surface of a semiconductor substrate such as a germanium wafer.

The water contained in the wetting agent of the present embodiment is preferably one in which the amount of impurities which does not inhibit the action of the wetting agent is small. For example, ion-exchange water, pure water, ultrapure water, distilled water, etc. are mentioned.

In the wetting agent of the present embodiment, other components may be further contained within a range that does not inhibit the action of the wetting agent.

Examples of the other components include a chelating agent such as an aminocarboxylic acid chelating agent and an organic phosphonic acid chelating agent, an oxygen alkylene polymer such as polyethylene glycol or polypropylene glycol, and a polyoxyalkylene fatty acid ester. A polyoxyalkylene adduct such as a polyoxyalkylene sorbitan fatty acid ester or a nonionic surfactant such as a copolymer of a plurality of oxygen alkyl groups.

The wetting agent of the present embodiment may be previously adjusted to a high concentration liquid having a concentration higher than that required at the time of use, and may be diluted at the time of use.

In the case of adjusting to the high concentration liquid, the storage and transportation of the wetting agent are facilitated.

In the case of adjusting to a high-concentration liquid, for example, a concentration adjusted to be diluted 5 times to 100 times, preferably 20 times to 60 times, is used.

By using the wetting agent for a semiconductor substrate of the present embodiment on a semiconductor substrate such as a semiconductor wafer before or after polishing, the wettability of the surface of the substrate after polishing can be improved, and the surface defects of the substrate can be sufficiently reduced.

The wetting agent for a semiconductor substrate of the present embodiment can also be used, for example, as a cleaning agent for rinsing the composition for polishing after polishing the wafer. By using the cleaning agent, the residual abrasive grains and the like of the polishing composition after polishing can be washed, and surface defects of the wafer can be reduced, and the wettability of the surface of the wafer can be improved.

Next, the polishing composition of the present invention will be described.

The polishing composition of the present embodiment is a composition containing hydroxyethyl cellulose, water, and abrasive grains, and the hydroxyethyl cellulose has a radius of inertia of 56 nm or more and 255 nm or less, and has a contact angle of 10 Above ° and below 32 °.

The hydroxyethyl cellulose contained in the polishing composition of the present embodiment is the same as the hydroxyethyl cellulose contained in the above-mentioned semiconductor substrate wetting agent.

In general, when the water-soluble polymer and the abrasive particles are contained together in the polishing composition, there is a problem in that the abrasive grains in the composition are easily aggregated.

In particular, a water-soluble polymer having a large molecular weight tends to adhere to the abrasive grains, and as a result, the problem of aggregation of the abrasive grains is further promoted.

In the polishing composition of the present embodiment, by containing hydroxyethyl cellulose having a specific range of the radius of inertia and the contact angle as a component for improving wettability, aggregation of the abrasive grains in the composition can be suppressed.

The content of the hydroxyethylcellulose in the polishing composition is not particularly limited. For example, the concentration at the time of use is 0.1 ppm or more and 10000 ppm or less, preferably 10 ppm or more and 6000 ppm or less.

When the content of the hydroxyethyl cellulose is in the above range, the insolubility of the surface of the object to be polished can be sufficiently improved while suppressing the generation of the insoluble material.

Further, aggregation of the abrasive grains can be sufficiently suppressed.

The abrasive grains are not particularly limited as long as they are used for polishing the substrate such as a semiconductor wafer, and examples thereof include known abrasive particles such as cerium oxide, aluminum oxide, cerium oxide, and zirconium oxide.

Among them, abrasive grains containing cerium oxide such as colloidal cerium oxide or cerium oxide are preferable, and it is particularly preferable because the colloidal cerium oxide is less likely to cause surface defects such as damage due to abrasive grains.

The content of the abrasive grains in the polishing composition is not particularly limited, for example, when used. The concentration is, for example, 0.01% by mass or more and 10% by mass or less, preferably 0.1% by mass or more and 1% by mass or less.

When the content of the abrasive grains is in the above range, the abrasiveness can be maintained and the abrasive grain residue adheres to the surface of the substrate after the polishing.

The polishing composition of the present embodiment may contain the wetting agent and the abrasive grains of the present embodiment. In other words, the polishing composition obtained by adding abrasive grains to the wetting agent for a semiconductor substrate as described above may be used.

The polishing composition of the present embodiment may further contain other components.

Examples of the other components include a chelating agent such as an aminocarboxylic acid chelating agent and an organic phosphonic acid chelating agent, an oxygen alkylene polymer such as polyethylene glycol or polypropylene glycol, and a polyoxyalkylene fatty acid ester. A polyoxyalkylene adduct such as a polyoxyalkylene sorbitan fatty acid ester or a nonionic surfactant such as a copolymer of a plurality of oxygen alkyl groups.

The wettability of the surface of the semiconductor substrate polished by the polishing composition of the present embodiment can be sufficiently improved, and the surface defects of the substrate can be sufficiently reduced.

Moreover, the aggregation of the abrasive grains which may cause haze can be suppressed, and the haze after polishing can be further suppressed.

The polishing composition of the present embodiment may be previously adjusted to a high concentration liquid having a concentration higher than that required at the time of use, and may be diluted at the time of use.

When it is adjusted to the high concentration liquid, the storage and transportation of the polishing composition are facilitated.

Further, in the case of adjusting to the high-concentration liquid, for example, a concentration adjusted to be diluted from 5 times to 100 times, preferably from 20 times to 60 times, is used.

The semiconductor substrate treated with the wetting agent for a semiconductor substrate or the polishing composition of the present embodiment has a good wettability on the surface and a small surface defect.

The hydroxyethyl cellulose improves the wettability of the surface of the substrate to be treated in the state of an aqueous solution, but on the other hand, it is likely to cause an insoluble substance. The insoluble matter The reason why the surface of the substrate is increased by causing the haze or the LPD value to rise due to adhesion to the surface of the substrate.

The wetting agent for a semiconductor substrate or the polishing composition of the present embodiment contains hydroxyethyl cellulose having a specific range of inertia radii and contact angle as described above, so that an insoluble substance is less likely to be generated, and the surface of the substrate can be reduced. defect.

The surface of the substrate after the treatment with the wetting agent for a semiconductor substrate or the polishing composition of the present embodiment is, for example, a foreign matter measured by a surface defect inspection device such as a confocal optical system laser microscope (MGICS M5640, manufactured by Lasertec). The number of so-called surface defects (Defect) such as dirt, damage, and particle residue is 3,000 or less, preferably 2,000 or less, and more preferably 1,000 or less on a circular substrate of 12 inches per sheet.

As described above, the wetting agent for a semiconductor substrate of the present invention contains hydroxyethyl cellulose and water, and the hydroxyethyl cellulose has a radius of inertia of 56 nm or more and 255 nm or less, and the contact angle is 10 or more and 32. ° below. In other words, since the wetting agent for a semiconductor substrate of the present invention contains hydroxyethylcellulose, the wettability of the surface of the semiconductor substrate can be improved. Further, since the inertia radius and the contact angle of the hydroxyethyl cellulose are in the above range, the generation of the insoluble matter can be suppressed in the aqueous solution. Therefore, the wettability of the surface of the substrate can be sufficiently improved, and at the same time, surface defects such as minute damage or dirt on the surface of the substrate due to the insoluble matter can be sufficiently reduced.

In the present invention, when the pH of the wetting agent for a semiconductor substrate is 9.0 or more and 11.0 or less, the wettability of the semiconductor substrate can be more sufficiently improved and the surface defects of the substrate surface can be more sufficiently reduced.

Further, the polishing composition of the present invention contains hydroxyethyl cellulose, water, and abrasive grains, and the hydroxyethyl cellulose has a radius of inertia of 56 nm or more and 255 nm or less, and a contact angle of 10 or more and 32°. the following.

Further, the polishing composition of the present invention may have a pH of 9.0 or more and 11.0 or less.

As described above, according to the present invention, the wettability of the surface of the semiconductor substrate can be sufficiently improved At the same time, the surface defects of the substrate can be sufficiently reduced.

Further, the wetting agent for a semiconductor substrate and the polishing composition of the present embodiment are as described above, but the embodiments disclosed herein are considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the scope of the claims and not the description of the claims.

[Examples]

Hereinafter, embodiments of the invention will be described, but the invention is not limited thereto.

"Hydroxyethyl cellulose"

Six different molecular weight hydroxyethyl celluloses (HEC 1-6) shown in Table 1 below were prepared.

0.3% by mass of each HEC, abrasive grains (cerium oxide produced by a sol-gel method, particle diameter: 70 nm by dynamic light scattering method), 9.5% by mass, and 0.5% by mass of ammonia (% by mass of NH ₃ ) The residual water is mixed to obtain the polishing compositions 1 to 6.

The polishing composition was diluted 31 times with water, and a wafer (12 inches) as a workpiece was polished under the following polishing conditions, and the surface of the wafer after polishing was wetted by the following method. The number of properties, surface defects, and pH were measured, and the results obtained are shown in Table 1.

Grinding conditions

Grinding device: SPP800S (manufactured by Okamoto Machine Co., Ltd.)

Polishing pad: Supreme RN-H (manufactured by NITTA-HAAS)

Platen speed: 40rpm

Grinding load: 100gf/cm ²

Flow rate: 0.6L/min

Abrasive: 12 inch Silicon wafer

Grinding time: 300sec

Wettability

Wettability was evaluated by the following method.

The wafer polished under the above polishing conditions was evaluated by visual observation. The evaluation criteria were ○ (good) when it was confirmed that the entire surface of the wafer immediately after polishing was wetted.

"Method for Measuring Surface Defects"

The surface defect (Defect) is obtained by washing the wafer polished under the above-described polishing conditions with an ammonia/hydrogen peroxide mixed solution, and then measuring it using a measuring device (MAGICS M5640 (manufactured by Lasertec)) (Edge Exclusion) EE: 5mm, clipping level: D37mV).

Further, for each HEC, the inertia radius, the absolute molecular weight, and the contact angle were measured by the following methods.

"Method for Measuring Inertia Radius and Absolute Molecular Weight"

The inertia radii of the hydroxyethylcellulose in the composition were measured using each of the polishing compositions 1 to 6 described above.

For the measurement of the radius of inertia, firstly, each sample of the concentration of hydroxyethylcellulose of 1 mg/ml, 2 mg/ml, 3 mg/ml, and 4 mg/ml was prepared, and a static light scattering photometer SLS-6500 (manufactured by Otsuka Electronics Co., Ltd.) was used. Each sample was measured at a measurement angle of 60/90/120/150 degrees, and the inertia radius and the absolute molecular weight were calculated by Zimm square root map analysis.

"Contact angle"

A 0.3% by mass aqueous solution of each HEC was prepared, and the contact angle of the solution was dropped onto a TEOS wafer having a surface roughness (Ra) of 10 angstroms (1 nm) using an automatic contact angle meter DM500 (manufactured by Kyowa Interface Chemical Co., Ltd.). Contact angle measurement.

For the measurement method, 0.1 ml of the HEC aqueous solution was filled into the syringe, and the HEC aqueous solution was discharged from the injection needle to the TEOS wafer, and attached to the surface of the wafer, and the CCD camera was used to obtain the separation from the droplet and the needle tip after 1 second. In the state, the contact angle of the TEOS substrate with the liquid was calculated using the θ/2 method.

pH

The pH of each composition at a liquid temperature of 25 ° C was measured using a pH meter (manufactured by Horiba, Ltd.).

According to Table 1, the wettability of the polished wafer surface of all the examples and the comparative examples was good, but in the comparative example using HEC having an inertia radius of less than 560 angstroms (56 nm) and a contact angle exceeding 32°, LPD was used. The value is higher and the reduction in surface defects is not sufficient.

Claims (4)

A wetting agent for a semiconductor substrate comprising hydroxyethylcellulose and water, wherein the hydroxyethylcellulose has a radius of inertia of 56 nm or more and 255 nm or less, and a contact angle of 10° or more and 32° or less. The wetting agent for a semiconductor substrate according to claim 1, which has a pH of 9.0 or more and 11.0 or less. A polishing composition comprising hydroxyethyl cellulose, water, and abrasive grains, wherein the hydroxyethyl cellulose has a radius of inertia of 56 nm or more and 255 nm or less, and a contact angle of 10° or more and 32° or less. The polishing composition according to claim 3, which has a pH of 9.0 or more and 11.0 or less.