TW201930541A - Polishing composition - Google Patents

Abstract

Provided is a polishing composition capable of reducing device vibrations. This polishing composition comprises colloidal silica, a water-soluble polymer, a basic compound, water, and a vibration suppression agent which is a polymer having an ethylene oxide group and a weight average molecular weight of 1,500 to 30,000. The molar concentration of the vibration suppression agent is 6.9 * 10<SP>-10</SP> mol/g or higher. The product of the mass concentration of the vibration suppression agent and the weight average molecular weight of the ethylene oxide group portion per molecule of the vibration suppression agent is 8.0 * 10<SP>-2</SP> or greater. In the vibration suppression agent, the proportion occupied by the ethylene oxide group within alkylene oxide groups is 80% or greater in terms of weight average molecular weight.

Description

Grinding composition

This invention relates to a polishing composition.

Ultra-precision machining is an extremely important technology in the manufacture of semiconductor products. In recent years, with the miniaturization of LSI devices, there has been a tendency for the surface roughness or flatness of semiconductor wafers after precision polishing to become stricter.

In the past grinding, the main focus is on the amount of grinding. However, it is known that the surface quality of a semiconductor wafer after one polishing affects the surface quality after secondary polishing or final polishing. Therefore, it is considered that in the future polishing, the current grinding amount is maintained and a higher level of wafer surface quality is sought.

Japanese Laid-Open Patent Publication No. 2016-124943 discloses a polishing composition comprising a polyvinyl alcohol-based water-soluble polymer and a piperidine compound as a polishing composition capable of reducing the surface roughness of the wafer without lowering the polishing rate.

In one grinding of a 300 mm wafer, two-side grinding is generally performed. The two-side grinding system performs grinding by sandwiching a wafer held by a dedicated carrier between a lower plate and a lower plate attached to the pad.

In the case of primary polishing, in order to reduce the thickness of the tantalum wafer, the polishing composition may contain a water-soluble polymer. In the case of performing double-side polishing using a polishing composition containing a water-soluble polymer, there is a case where vibration is generated in the device by friction between the carrier and the polishing pad. In order to improve the processing efficiency, if the load or the number of rotations is increased, the vibration of the device is increased, and the quality of the wafer is lowered or the device is malfunctioning.

It is an object of the present invention to provide a polishing composition which can reduce the vibration of a device.

The polishing composition according to one embodiment of the present invention comprises colloidal cerium oxide, a water-soluble polymer, a basic compound, water, and a vibration inhibitor having a weight average molecular weight of 1,500 to 30,000 and having an oxirane group. The molar concentration of the vibration inhibitor is 6.9×10 ^-10 mol/g or more, and the product of the weight average molecular weight of the oxirane moiety per molecule of the vibration inhibitor and the mass concentration of the vibration inhibitor is 8.0 × 10 ^-2 or more, in the vibration inhibitor, the ratio of the weight average molecular weight of ethylene oxide to the alkylene oxide group is 80% or more.

According to the present invention, a polishing composition which can reduce the vibration of the device is obtained.

The inventors of the present invention have conducted various studies in order to solve the above problems. As a result, it has been found that the polishing composition contains a weight-average molecular weight of 1,500 to 30,000 and a specific concentration of the polymer having an oxirane group, thereby suppressing vibration of the apparatus. It is considered that the principle is unknown, and the oxirane group is adsorbed on the mat or the carrier to improve the contact state of the mat or the carrier with the water-soluble polymer.

The polymer having an oxirane group and a copolymer of a propylene oxide group as a hydrophobic group are contained in the form of a surfactant in the form of a surfactant. However, if a polymer containing a large amount of an epoxy group other than an oxirane group is used for the double-side polishing of a semiconductor wafer, the shape of the laser mark (the unevenness indicating the crystal orientation of the semiconductor wafer) is remarkable. deterioration. In order to suppress deterioration of the shape of the laser mark, it is necessary to set the ratio of the weight average molecular weight of the ethylene oxide group to the alkylene oxide group in the polymer used as the vibration inhibitor to be 80% or more.

The present invention has been completed based on these findings. Hereinafter, the polishing composition of one embodiment of the present invention will be described in detail.

A polishing composition according to an embodiment of the present invention comprises colloidal cerium oxide, a water-soluble polymer, a basic compound, water, and a vibration inhibitor.

Colloidal cerium oxide can be used in the field. The particle diameter of the colloidal cerium oxide is not particularly limited, and for example, a secondary average particle diameter of 20 to 130 nm can be used.

The content of the colloidal cerium oxide is not particularly limited, and is, for example, 0.15 to 20% by mass based on the entire polishing composition (stock solution). The polishing composition is diluted to 10 to 80 times at the time of polishing and used. The polishing composition of the present embodiment is preferably used in which the concentration of cerium oxide is diluted to 100 to 5000 ppm (ppm by mass. The same applies hereinafter).

The water-soluble polymer is adsorbed on the surface of the semiconductor wafer to modify the surface of the semiconductor wafer. Thereby, the uniformity of the grinding is improved, and the surface roughness can be reduced. The water-soluble polymer is not limited thereto, and hydroxyethyl cellulose (HEC), hydroxyethyl methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, cellulose acetate, methyl cellulose, or the like can be used. An ethylene polymer such as cellulose, polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP), a glycoside (glycoside), a polyhydric alcohol or the like.

The water-soluble polymer is preferably a polymer having no epoxyalkyl group. Among the above water-soluble polymers, those having a high molecular weight and easily infiltrating into water molecules are preferable, and HEC is particularly preferable.

The content of the water-soluble polymer is not limited thereto, and is, for example, 0.01 to 1.2% by mass based on the entire polishing composition (stock solution).

The alkaline compound etches the surface of the semiconductor wafer for chemical polishing. The basic compound is, for example, an amine compound, an inorganic base compound or the like.

The amine compound is, for example, a primary amine, a secondary amine, a tertiary amine, a quaternary ammonium salt and a hydroxide thereof, a heterocyclic amine or the like. Specific examples include ammonia, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrabutylammonium hydroxide (TBAH), methylamine, dimethylamine, and trimethylamine. Amine, ethylamine, diethylamine, triethylamine, hexylamine, cyclohexylamine, ethylenediamine, hexamethylenediamine, diethylenetriamine (DETA), triethylenetetramine, tetraethylenepentamine, Pentaethylene hexamine, monoethanolamine, diethanolamine, triethanolamine, N-(β-aminoethyl)ethanolamine, anhydrous piperazine, piperazine hexahydrate, 1-(2-aminoethyl) piperidine, N -methylpiperidin, piperazine hydrochloride, cesium carbonate, and the like.

Examples of the inorganic base compound include a hydroxide of an alkali metal, a salt of an alkali metal, a hydroxide of an alkaline earth metal, a salt of an alkaline earth metal, and the like. The inorganic base compound is specifically potassium hydroxide, sodium hydroxide, potassium hydrogencarbonate, potassium carbonate, sodium hydrogencarbonate, sodium carbonate or the like.

The above basic compounds may be used singly or in combination of two or more. Among the above basic compounds, ammonia, an amine, an alkali metal hydroxide or an alkali metal carbonate is particularly preferable.

The content of the basic compound (the total amount when two or more kinds are contained) is not particularly limited, and is, for example, 0.01 to 1.2% by mass based on the entire polishing composition.

The polishing composition of the present embodiment further contains a polymer having a weight average molecular weight of 1,500 to 30,000 and having an oxirane group as a vibration inhibitor. In other words, the polishing composition of the present embodiment contains one or more kinds of polymers that function as vibration inhibitors in addition to the water-soluble polymer.

The polymer which can be used as a vibration inhibitor is, for example, polyethylene glycol (PEG), glycerin derivative, polysalamine, ethylene glycol diglycidyl ether, polyol derivative, fatty acid hydrocarbon ester, and alkane. Alkylamine derivatives, organic polyoxoxanes, and the like.

The vibration inhibitor forms a layer by being adsorbed on the surface of the carrier or pad, and changes the contact state and suppresses vibration. When the weight average molecular weight is less than 1,500, the thickness of the adsorption layer is small, and the effect as a vibration inhibitor cannot be obtained. The lower limit of the weight average molecular weight of the polymer used as the vibration inhibitor is preferably 2,000, and more preferably 3,000. On the other hand, when the weight average molecular weight is more than 30,000, the number of molecules is reduced, and the adsorption layer is coarsely condensed, and the effect as a vibration inhibitor cannot be obtained. The upper limit of the weight average molecular weight of the polymer used as the vibration inhibitor is preferably 25,000, and more preferably 20,000.

In the polishing composition of the present embodiment, the molar concentration (in use) of the vibration inhibitor is 6.9 × 10 ^-10 mol / g or more. If the molar concentration of the vibration inhibitor is less than 6.9 × 10 ^-10 mol/g, the effect as a vibration inhibitor cannot be obtained. The lower limit of the molar concentration of the vibration inhibitor is preferably 1.0 × 10 ^-9 mol / g, more preferably 2.0 × 10 ^-9 mol / g. On the other hand, if the molar concentration of the vibration inhibitor is too high, the aggregation of the abrasive grains is likely to occur, and the adjustment as the polishing composition is more difficult. The upper limit of the molar concentration of the vibration inhibitor is preferably 5.0 × 10 ^-6 m, and more preferably 5.0 × 10 ^-8 mol / g.

In addition, the content of the vibration inhibitor in the polishing composition (stock solution) is not particularly limited, and is, for example, 0.005 to 0.5% by mass.

In the polishing composition of the present embodiment, the weight average molecular weight of the oxirane moiety per one molecule of the vibration inhibitor and the mass concentration of the vibration inhibitor in the polishing composition (hereinafter referred to as "W _EO"・Concentration".) is 8.0 × 10 ^-2 or more. Here, the mass concentration of the vibration inhibitor is a value obtained by dividing the mass of the vibration inhibitor in the polishing composition by the mass of the polishing composition (after dilution).

When the concentration of W _EO is less than 8.0 × 10 ^-2 , the vibration suppression effect cannot be obtained even if the molar concentration of the vibration inhibitor is 6.9 × 10 ^-10 mol / g or more. The lower limit of the W _EO concentration is preferably 1.0 × 10 ^-1 , more preferably 2.0 × 10 ^-1 . On the other hand, when the concentration of W _EO is too large, aggregation of the abrasive grains is likely to occur, and it is difficult to adjust the composition for polishing. The upper limit of the W _EO concentration is preferably 2.0, and more preferably 1.5.

In the vibration inhibitor, the ratio of the ethylene oxide group to the weight average molecular weight of the alkylene oxide group (hereinafter referred to as "W _EO /W _AO ") is 80% or more. If the W _EO /W _{AO is} less than 80%, the shape of the laser mark of the polished semiconductor wafer is significantly deteriorated. W _EO /W _{AO is} preferably 90% or more.

The polishing composition of the present embodiment may further contain a pH adjuster. The pH of the polishing composition of the present embodiment is preferably 8.0 to 12.0.

In addition to the above, the polishing composition of the present embodiment can be optionally formulated with a formulation generally known in the field of polishing compositions.

The polishing composition of the present embodiment is produced by appropriately mixing colloidal cerium oxide, a water-soluble polymer, a basic compound, a vibration inhibitor, and other formulation materials, and adding water. The polishing composition of the present embodiment is produced by sequentially mixing colloidal cerium oxide, a water-soluble polymer, a basic compound, a vibration inhibitor, and other compounding materials in water. As a method of mixing these components, a method commonly used in the technical field of a composition for polishing, such as a homogenizer or an ultrasonic wave, is used.

The polishing composition described above is diluted with water to an appropriate concentration and then used for polishing a semiconductor wafer.

The polishing composition of the present embodiment can be preferably used for polishing both sides of a tantalum wafer. The polishing composition of the present embodiment is particularly suitable for the case where the tantalum wafer is polished on both sides using a glass epoxy resin carrier.
Example

Hereinafter, the present invention will be more specifically described by way of examples. The invention is not limited to the embodiments.

The polishing compositions of Examples 1 to 7 and Comparative Examples 1 to 15 shown in Table 1 were produced.
[Table 1]

The dosages in Table 1 are all before dilution (stock solution), and the rest is water. The polishing composition of Comparative Example 1 may contain a polymer corresponding to a vibration inhibitor. The colloidal cerium oxide system uses a secondary average particle diameter of 70 nm. The HEC system uses a weight average molecular weight of 500,000. As the polyol, polyoxyethylene methyl glucoside having a weight average molecular weight of 634 was used.

[Vibration Test 1]
The polishing composition described in Table 1 was diluted to 41 times, and two-side polishing of a 12-inch wafer was carried out using DSM20B-5P-4D manufactured by SpeedFam. As the polishing pad, EXTERION (registered trademark) SL-31 manufactured by Nittahaas Co., Ltd. was used. The polishing was performed for 3 minutes, and the presence or absence of buzzing and vibration of the device was investigated.

[Vibration Test 2]
The polishing composition described in Table 1 was diluted to 41 times, and a 12-inch glass epoxy resin was used as a material to be polished using POLI762 manufactured by G&P Co., Ltd., and the coefficient of friction was analyzed. Here, the glass epoxy resin is used as the material to be polished in order to simulate the rubbing state of the both surfaces of the carrier made of the glass epoxy resin. As the polishing pad, EXTERION (registered trademark) SL-31 manufactured by Nittahaas Co., Ltd. was used. The polishing composition was supplied at a rate of 300 mL/min, a surface pressure of 150 g/cm ² and a pilot pressure of 220 g/cm ² .

[Laser Marking Test]
When the polishing slurry Nanopure (registered trademark) NP6610 manufactured by Nittahaas Co., Ltd. was diluted to 31 times, 0.5 ppm of the vibration inhibitor described in Table 1 was added, and DSM20B-5P-4D manufactured by SpeedFam Co., Ltd. was used for 12 inches. Then both sides of the wafer are ground. After 30 minutes of grinding, the height of the laser marking was raised. Specifically, the Wyko NT9300 (non-contact type interference microscope) manufactured by Veeco Co., Ltd. was used to measure the end portion of the laser mark T7 code, and the height of the ridge was measured from the cross-sectional profile of the peripheral portion of the specific point.

Table 2 shows the molar concentration, W _EO · concentration, and W _EO /W _AO of the vibration inhibitor of the polishing composition after dilution 41 times, and the vibration measurement test 1, the vibration measurement test 2, and the laser mark measurement test. result.

[Table 2]

The results of the vibration measurement test 1 are shown in the column of "vibration" in Table 2.

The results of the vibration measurement test 2 are shown in the column of "head load" in Table 2. The numerical value in the same column indicates the amount of load reduction of the polishing head in the direction perpendicular to the load direction based on Comparative Example 1, and the larger the value, the higher the vibration suppression effect.

The results of the laser marking test are shown in the column of "Laser Mark" in Table 2. When the value of the same column is positive, it is represented by the shape in which the edge portion of the laser mark after polishing is protruded. The values in the same column are values normalized by the case of Comparative Example 2 being 100.

In the case of using the polishing compositions of Examples 1 to 7, no vibration of the device was generated, and the shape of the laser mark deteriorated within an allowable range.

The polishing composition of Comparative Example 1 did not contain a vibration inhibitor. Therefore, the vibration of the device is generated.

The polishing compositions of Comparative Examples 2 to 4 had a low W _EO concentration. Therefore, the vibration of the device is generated. Also, W _EO /W _{AO is} low, and the shape of the laser mark is also deteriorated.

The polishing compositions of Comparative Examples 5 and 6 had lower W _EO /W _AO . Therefore, the shape of the laser mark deteriorates.

In the polishing compositions of Comparative Examples 7 to 9, the vibration inhibitor had a low molar concentration. Therefore, the vibration of the device is generated.

In the polishing compositions of Comparative Examples 10 to 12, the W _EO concentration was low. Therefore, the vibration of the device is generated.

In the polishing compositions of Comparative Examples 13 to 15, the weight average molecular weight of the polymer blended as a vibration inhibitor was too large. Therefore, the vibration of the device is generated.

Fig. 1 is a scatter diagram in which the horizontal axis represents the molar concentration of the vibration inhibitor and the vertical axis represents the W _EO and concentration. In Fig. 1, a hollow mark indicates that no vibration is generated, and a solid mark indicates that vibration is generated. As shown in Fig. 1, it is understood that the molar concentration is 6.9 × 10 ^-10 mol/g or more, and the W _EO concentration is 8.0 × 10 ^-2 or more, whereby the vibration of the device can be suppressed.

The embodiments of the present invention have been described above. The above embodiments are merely examples for carrying out the invention. Therefore, the present invention is not limited to the above-described embodiments, and the above-described embodiments can be appropriately modified and implemented without departing from the spirit and scope of the invention.

Fig. 1 is a scatter diagram in which the horizontal axis represents the molar concentration of the vibration inhibitor and the vertical axis represents the W _EO and concentration.

Claims (2)

A polishing composition comprising: colloidal cerium oxide, a water-soluble polymer, a basic compound, water, and a vibration inhibitor having a weight average molecular weight of 1,500 to 30,000 and having an oxirane group, the vibration The molar concentration of the inhibitor is 6.9×10 ^-10 mol/g or more, and the product of the weight average molecular weight of the above-mentioned ethylene oxide group portion per molecule of the vibration inhibitor and the mass concentration of the vibration inhibitor is 8.0×10. ^{In the} above vibration inhibitor, the ratio of the ethylene oxide group to the weight average molecular weight of the alkylene oxide group is 80% or more. A polishing composition according to claim 1, wherein The above water-soluble polymer is hydroxyethyl cellulose.