JP2012011488A - Method for measuring silica particulate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect silica particulates for polishing remaining on a surface of a precision component.SOLUTION: Silica particulates remaining on a precision component subjected to a polishing process of polishing a precision component basically constituted of silicon dioxide with polishing liquid containing silica particulates with impurities being contained in its composition, and a cleaning process of cleaning the precision component after the polishing process are measured. The method for measuring silica particulates includes a solving step of solving a surface of the precision component with a solution, and a quantitative determination step of quantitatively determining the silica particulates out of impurities in the solution through the solving step. In one embodiment, the method includes a defect counting step of detecting impurities contained in the silica particles by optically counting defective parts on the surface of the precision component before the solving step after the cleaning process. Impurities can be detected as a marker in a sample inspection process 10.

Description

  The present invention relates to a method for measuring silica fine particles.

  A precision part containing silicon dioxide, for example, a precision part represented by a hard disk drive (HDD) or a single crystal part represented by a semiconductor wafer is manufactured through a polishing process. In such a polishing process, a polishing liquid mainly containing silica-based abrasive grains is used.

  As a method for producing a raw material for silica-based abrasive grains, for example, Patent Documents 1 and 2 disclose a method for producing silica fine particles such as colloidal silica used for final polishing. It has been considered that such silica fine particles are ideal to remove impurities from the viewpoint of stability and the like.

  FIG. 1 is a process flow diagram showing a manufacturing process of a conventional hard disk drive using a conventional glass substrate. As shown in FIG. 1, when a precision component is a glass substrate (substrate) of an information recording medium, the glass substrate is manufactured through a glass material melting step 1 and a grinding step 2. Further, this glass substrate is polished in the polishing step 3. Silica-based abrasive grains such as colloidal silica produced by the methods of Patent Documents 1 and 2 in the final process (usually, the polishing process 3 is designed to increase the polishing accuracy step by step through a plurality of steps). It polishes with the polishing liquid containing. In addition, the method of manufacturing a glass substrate using a silica-type abrasive grain is disclosed by patent document 3, 4, for example.

  In order to ensure the quality of precision parts, the polished precision parts are inspected by an optical surface analyzer (OSA), a particle detector, or the like. OSA measures the amount of foreign matter in precision parts, for example, with a resolution of 0.22 microns (220 nm) to 2,000 microns (2,000,000 nm). In addition, the particle detector scans the wafer surface with laser light and measures the light scattering intensity from the particles and the like, thereby determining the position and size of a foreign matter or COP (Crystal Originated Particle) and the like as a bright point defect (Light Point). It is a detection device recognized as Defect (LPD).

JP 2001-11433 A International Publication WO2008 / 072637 JP 2008-246645 A JP 2008-101132 A

  Silica fine particles used for final polishing tend to be smaller in size every year. At present, silica fine particles of about several nm to several tens of nm smaller than the wavelength of light are used. Therefore, OSA could not measure silica fine particles. On the other hand, even if a general high frequency inductively coupled plasma mass spectrometer (ICP-MS) is used, if the precision part is based on silicon dioxide, the precision part silicon and the remaining polishing liquid silicon Therefore, it was impossible to detect a defective product to which silica fine particles for polishing adhered. As a result, even if a defective product in which the silica fine particles are excessively adhered is generated in the polishing process 3, there is no way to detect the defect, and conventionally, the film forming process 5 and the assembling process 6 are directly performed. As a result, a defect in the polishing process 3 was detected in the final inspection process 7, resulting in poor yield and low productivity.

  This invention is made | formed in view of the said malfunction, and makes it a subject to provide the measuring method of the silica particle which can detect this, when it remains on the surface of a precision component.

  In order to solve the above problems, the present invention provides a polishing step of polishing a precision component based on silicon dioxide with a polishing liquid containing silica fine particles containing impurities in the composition, and cleaning the precision component after the polishing step. A method for measuring silica fine particles for measuring silica fine particles remaining in the precision component that has undergone a cleaning process, wherein after the cleaning process, a dissolution step of dissolving the surface of the precision component with a solution, and the dissolution step And a quantitative determination step of quantifying the silica fine particles from the amount of impurities in the passed solution. In this aspect, the impurities contained in the silica fine particles for polishing function as a marker. Therefore, when inspecting a precision part, the impurities contained in the silica fine particles can be detected and the silica fine particles can be quantified based on the detected impurities. . The function as the marker makes it possible to quantify fine silica particles (for example, particle diameters of 1 nm to 100 nm) that have been difficult to detect in the past. As a result, since it is possible to determine the quality of precision parts in a process upstream of the prior art, the yield of subsequent processes can be improved and productivity can be increased. The precision part may be a crystal substrate such as a semiconductor wafer or a glass substrate as long as it is based on silicon dioxide. Furthermore, the glass substrate is exemplified by a glass substrate for hard disk. In the case of a glass substrate for hard disk, “elements contained in precision parts” are exemplified by sodium, potassium and the like. In the case of a semiconductor wafer, gallium and indium are exemplified. Further, any of the enumerated impurities has low ionization energy (less than 9.26 eV), and the impurities are analyzed by ICP-MS, and based on this, silica fine particles can be easily quantified.

  Another aspect of the present invention includes a polishing step of polishing a precision component based on silicon dioxide with a polishing liquid containing silica fine particles containing impurities in the composition, and a cleaning step of cleaning the precision component after the polishing step. The silica fine particle measurement method measures the silica fine particles remaining in the precision component that has undergone the cleaning, and after the cleaning step, optically counts defective sites on the surface of the precision component, A method for measuring silica fine particles, comprising a defect counting step for detecting the impurities contained therein. In this aspect, an apparatus for optically detecting impurities contained in silica fine particles by using a polishing liquid containing silica fine particles containing impurities (for example, a particle detection device for counting luminance defects in a semiconductor wafer). The silica fine particles can be quantified based on the defect count.

  The defect counting step preferably detects a bright spot defect by scanning the surface of the semiconductor wafer as the precision component with a laser beam and measuring the light scattering intensity.

  In each embodiment, the impurity is titanium, vanadium, zinc, gallium, germanium, rubidium, strontium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, indium, tin, antimony, tellurium, cesium, barium, hafnium, It is preferably an element selected from the group of tantalum, tungsten, rhenium, iridium, platinum, gold, lead, bismuth, and rare earth elements. In this embodiment, all the impurities have low ionization energy (less than 9.26 eV), and the impurities are analyzed by ICP-MS, and based on this, the silica fine particles can be easily quantified.

  In a preferred embodiment, the silica fine particles are colloidal silica.

  In a preferred embodiment, the silica fine particles have a particle size of 1 nm to 100 nm. In this embodiment, the particle size is shorter than the wavelength of light and can exhibit extremely good polishing performance. On the other hand, due to impurities contained in the silica fine particles, the silica fine particles contained in the polishing liquid are removed from the precision component itself. It becomes possible to distinguish from the silicon component.

  In a preferred embodiment, the content of the impurities ranges from 1 ppm to 10,000 ppm of the total mass. In this aspect, it becomes the range which can exhibit an identification function, maintaining performance suitable as polishing liquid.

  In a preferred embodiment, the step of polishing the precision component is used in the final polishing step of the precision component.

  In a preferred embodiment, the element as the impurity is titanium, vanadium, gallium, germanium, rubidium, strontium, zirconium, niobium, molybdenum, rhodium, palladium, silver, indium, tin, cesium, barium, hafnium, tantalum, tungsten, rhenium. , Lead, bismuth, and rare earth elements. In this embodiment, among the group of elements selected as the impurity, an isotope abundance ratio of 70% or more with one atomic weight and a small number of the same weight bodies with the atomic weight are selected as the impurities, Sensitivity can be further improved.

  In a preferred embodiment, the element as the impurity is selected from rare earth elements. In this embodiment, since a stable rare earth element is selected from the group of elements selected as impurities, it is easy to include them in the colloidal silica fine particles as impurities.

  In a preferred embodiment, the element as the impurity is at least one of ruthenium, rhodium, and palladium. In this embodiment, an element that is soluble in hydrochloric acid is selected from the group of elements selected as impurities, so that isolation is facilitated.

  In a preferred embodiment, the element as the impurity is at least one of germanium, strontium, and tellurium. In this embodiment, an element that is easily soluble in nitric acid is selected from the group of elements selected as impurities, and thus it is easy to remove during cleaning. On the other hand, when hydrochloric acid, sulfuric acid, etc. are used for cleaning, iron adheres to them, which is not preferable.

  In a preferred embodiment, the element as the impurity is at least one of tungsten, tantalum, molybdenum, niobium, and zirconium. In this embodiment, the group of elements selected as impurities is relatively stable to acids other than hydrofluoric acid and does not elute during processing or cleaning, so that handling becomes convenient.

    As described above, according to the present invention, it is possible to detect the silica fine particles for polishing remaining on the surface of the precision component, and it is possible to quantify the colloidal silica based on the detection. As a result, it is possible to determine the quality of precision parts in the upstream process. As a result, the yield in the subsequent process is improved, and the productivity can be increased.

It is a process flow figure showing the manufacturing method of the conventional glass substrate. It is a process flow figure showing a manufacturing method of a glass substrate concerning an embodiment of the present invention. It is a process flow figure showing a manufacturing method of a semiconductor wafer concerning an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[Precision parts]
The present embodiment can be applied to various precision parts. The precision parts are basically based on silicon dioxide, and examples thereof include a glass substrate for hard disk, a glass material for plasma display, and a semiconductor wafer.

For example, as a glass material of a glass substrate for hard disk, Li ₂ O is 3.6% by mass, Na ₂ O is 11.2% by mass, K ₂ O is 0.4% by mass, MgO is 0.6% by mass, CaO 1.6% by mass, Al ₂ O ₃ 14.9% by mass, SiO ₂ 64.5% by mass, ZrO ₂ 2.0% by mass, CeO ₂ 0.5% by mass, SnO ₂ 0 7% by mass is preferred.

The semiconductor wafer is basically a single crystal obtained by purifying high-purity metallic silicon.
[Method for producing colloidal silica containing impurities]
Colloidal silica as silica fine particles is prepared by hydrolysis and polycondensation reaction of alkyl silicate in a reaction medium. At this time, the impurities can be contained in the colloidal silica by dissolving the impurities in the reaction medium for synthesis. This embodiment is effective for producing colloidal silica having a particle diameter of 3 nm to 100 nm.

  The reaction medium contains alkali metals such as ammonia, sodium, potassium and lithium, alkalis such as water-soluble amines and quaternary ammonium hydroxides. In particular, alkali metal hydroxides have high reactivity and are preferably used. In order to obtain colloidal silica containing no alkali metal, a nitrogen-containing basic compound is used.

  The alkyl silicate used in this embodiment is a silicic acid monomer or an alkyl ester of a silicic acid oligomer having a polymerization degree of 2 to 10. As this alkyl group, those having 1 to 3 carbon atoms are preferable. Also, mixed esters having different alkyl groups in the molecule and mixtures of these alkyl silicates can be used. Examples of preferred alkyl silicates include tetramethyl silicate, tetraethyl silicate, methyl triethyl silicate and the like.

  Impurities include titanium, vanadium, zinc, gallium, germanium, rubidium, strontium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, indium, tin, antimony, tellurium, cesium, barium, hafnium, tantalum, tungsten, Rhenium, iridium, platinum, gold, lead, bismuth, and rare earth elements are preferred. In practicing the present invention, it is preferable to select one or more suitable elements from the group of elements described above. Impurities are, in principle, provided that they are not in the composition constituting the precision part, not in the environment where the precision part is encountered, can be analyzed by ICP-MS, are stable, and are not toxic. In particular, rare earth elements are effective for this.

  Silicon is excluded from the group of elements because it is included in the composition of precision parts. When the precision component is a magnetic disk glass substrate, elements such as strontium, titanium, and zinc are excluded from the group because they may be included in the substrate. When the precision component is a semiconductor wafer, gallium and indium may be excluded from the above group.

  Alkali metals (except Rb and Cs), iron, chlorine, nickel and aluminum are excluded from the element group in this embodiment because they exist in the environment or process encountered by precision parts.

  From the viewpoint of being measurable by ICP-MS, an element having high ionization energy such as sulfur (9.26 eV or more) is also unsuitable as a marker because of its high measurement limit value. Suitable are titanium, vanadium, gallium, germanium, rubidium, strontium, zirconium, niobium, molybdenum, rhodium, palladium, silver, indium, tin, cesium, barium, hafnium, tantalum, tungsten, rhenium, lead, bismuth, and It is a rare earth element.

  As a stable material, a rare earth element is preferable.

  From the viewpoint of toxicity, those that are expected to have adverse effects on the environment and human body, such as beryllium, boron and arsenic, are excluded.

  Impurities satisfying these conditions are added to the reaction medium, alkyl silicate is further added to the reaction medium containing impurities, and the reaction medium is brought into contact with the alkyl silicate at a temperature from 45 ° C. to the boiling point of the reaction medium. While allowing the silicate to undergo a hydrolysis reaction, the polymerization reaction of silicic acid in the reaction medium generated thereby can be advanced. As the silicic acid polymerization reaction proceeds, silica core particles containing impurities are generated in the reaction medium, and colloidal silica having a uniform particle size of 3 nm to 100 nm, preferably 5 nm to 100 nm, is generated by the particle growth. .

For example, 3% by weight of sodium hydroxide is added as an alkaline catalyst, 2% by weight of trisodium citrate is added as a dispersing agent, and yttrium oxide, manganese dioxide, and zinc chloride are dissolved as impurities in an amount of 1% by weight. In another embodiment, tetraethyl silicate can be added to the aqueous solution. In that case, the content of yttrium oxide in the reaction medium is preferably 0.01% to 5.00%. This is because if it is too low, it cannot be detected, and if it is too high, the reaction may be inhibited. The reaction is carried out, for example, at 80 ° C., and after completion of the reaction, unreacted residues can be removed with a filter to produce colloidal silica containing about 100 ppm of yttrium (content is ICP after dissolving the colloidal silica with hydrofluoric acid). -Evaluated by MS).
[Polishing liquid]
The colloidal silica is mixed with a polishing particle dispersion as a dispersion medium and becomes a main component of a polishing liquid used for final polishing of various precision parts.

  The polishing particle dispersion according to this embodiment is water-soluble such as polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, (meth) acrylic acid (co) polymer, poly (meth) acrylamide (co) polymer, and ethylene glycol. Polymers and sulfonic acid, phosphoric acid, carboxylic acid, and nonionic surfactants are preferred.

  Further, the polishing particle dispersion according to the present embodiment can be used as a polishing liquid only by including the colloidal silica, but if desired, as an additive, a polishing accelerator, a surfactant, a heterocyclic ring can be used. You may add and use 1 or more types chosen from the group which consists of a compound, a pH adjuster, and a pH buffer. As the pH adjuster, an inorganic acid or an organic acid is used. For example, examples of the inorganic acid include nitric acid, sulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid, and the like, and nitric acid is preferable in terms of ease of handling. Acids that are highly erodible to glass such as hydrofluoric acid cannot be used because they cause scratches. Examples of the organic acid include oxalic acid and citric acid.

  In the polishing liquid according to the present invention, a conventionally known polishing accelerator can be used as necessary, although it varies depending on the type of precision component.

Next, a method for manufacturing precision parts based on silicon dioxide using the above-described polishing liquid will be described.
[Glass substrate manufacturing method]
Referring to FIG. 2, when the precision component is a glass substrate, a melting step 1 and a grinding step 2 are performed as in the prior art. Next, the polishing step 3 is performed using the polishing liquid containing colloidal silica produced in Embodiment 1 or 2, and then the cleaning step 4 is performed. Next, in this embodiment, a sample inspection process 10 is performed.

  In this sample inspection process 10, several samples are extracted and colloidal silica is measured. This measurement inspection includes a dissolution step of dissolving the surface of the glass substrate with a solution, and a determination step of quantifying colloidal silica from the amount of impurities in the solution that has undergone the dissolution step.

  The colloidal silica produced by the above-described embodiment is a particle having a uniform particle size of 3 nm to 100 nm, and thus is usually not detected by an optical surface analyzer (OSA). However, when the above-mentioned predetermined impurity is mixed, this impurity becomes a shadow, and detection by a high frequency inductively coupled plasma mass spectrometer (ICP-MS) becomes possible.

  In the dissolution step, the components can be analyzed by dissolving in a solution such as sulfuric acid. Various embodiments can be used as long as the inorganic acid is added to hydrofluoric acid, such as hydrofluoric acid and nitric acid, hydrofluoric acid and hydrochloric acid. is there. Moreover, since it becomes easy to measure by ICP-MS, it is preferable to dissolve in a solution containing hydrofluoric acid and nitric acid.

Next, in the quantification step, it is possible to quantify the colloidal silica containing the impurity by detecting the component of the impurity by ICP-MS.
[Method of manufacturing semiconductor wafer]
Referring to FIG. 3, when the precision component is a semiconductor wafer, ingot growth process 20, external grinding process 21, etching process 22, slashing process 23, chamfering process 24, lapping process 25, etching process 26, mirror polishing process 27, A cleaning process 28 and a sample inspection process 29 are performed.

  First, in the ingot growth step 20, a single crystal semiconductor ingot is grown by the Czochralski method (CZ method), the floating zone method (FZ method), or the like.

  In the external grinding step 21, the front end portion and the end portion of the single crystal semiconductor ingot are cut. In this external grinding step 21, the outer periphery of the semiconductor ingot is ground with a cylindrical grinder or the like in order to make the diameter uniform, and the outer peripheral shape is adjusted.

  In the etching step 22, etching is performed by being immersed in an etching solution as necessary.

  In the slashing step 23, an orientation flat or an orientation notch is applied to the block body so that the block body that has undergone the external grinding step 21 exhibits a specific crystal orientation. After this process, the block body is sliced with a wire saw or the like at a predetermined angle with respect to the rod axis direction to become a wafer.

  In the chamfering step 24, chamfering is performed on the periphery of the wafer sliced through the thrashing step S3 in order to prevent chipping and chipping of the peripheral portion. That is, the outer peripheral portion of the wafer is chamfered into a predetermined shape by the chamfering grindstone. Thereby, the outer peripheral portion of the wafer is formed into a predetermined rounded shape.

  In the lapping step 25, the concavo-convex layers on the front and back surfaces of the thin disk-like wafer generated in the slicing step and the like are flattened by lapping. In this lapping step, the wafer is placed between lapping surface plates parallel to each other, and a lapping solution that is a mixture of alumina abrasive grains, a dispersant, and water is poured between the lapping surface plate and the wafer. Then, rotation and rubbing are performed under pressure to wrap the front and back surfaces of the wafer. This increases the flatness of the wafer front and back surfaces and the parallelism of the wafer.

  In the etching step 26, the wafer that has undergone the lapping step S5 is immersed in an etching solution and etched. In this etching process, the work-affected layer introduced by the machining process such as the chamfering process 24 and the lapping process 25 is completely removed by etching.

In the mirror polishing step 27, for example, the surface of the wafer is polished in three stages.
(1) Outer peripheral polishing step First, the outer peripheral portion of the wafer that has undergone the etching step 26 is subjected to outer peripheral polishing. Thereby, the chamfered surface of the wafer is mirror finished. In the peripheral polishing step, the chamfered surface of the wafer is pressed against a polishing cloth while supplying a polishing liquid containing loose abrasive grains, and polished to a mirror surface.
(2) Rough Polishing Step Next, the surface of the wafer that has undergone the peripheral polishing step is roughly polished using a double-side polishing apparatus that simultaneously polishes the front and back surfaces or a single-side polishing apparatus that polishes the front and back surfaces one by one. In the rough polishing step, a predetermined surface of the wafer is pressed against a polishing cloth while supplying a polishing liquid containing free abrasive grains, and is polished with a polishing amount of 5 to 10 μm. Examples of the polishing cloth include a porous nonwoven cloth type polishing cloth in which a polyester felt is impregnated with polyurethane. The rough polishing may be performed in one step (primary polishing) or in multiple steps (primary polishing, secondary polishing,...). That is, the rough polishing means all polishing steps before final polishing for performing final mirror finish.
(3) Final polishing process The wafer that has undergone the rough polishing process is further subjected to final polishing using a double-sided simultaneous polishing apparatus that simultaneously polishes the front and back surfaces or a single-side polishing apparatus that polishes the front and back surfaces one by one. In the final polishing step, the polishing liquid of the present embodiment described above is pressed against the polishing cloth while being supplied to a predetermined surface of the wafer, and polished to a mirror surface with a polishing amount of 1 μm or less. Examples of the abrasive cloth include a two-layer suede-like abrasive cloth in which polyurethane is foamed on a nonwoven fabric base cloth. By this finish polishing, the mirror polishing is completed.

  In the cleaning step 28, the wafer that has undergone the mirror polishing step 27 is finished and cleaned. Specifically, it is cleaned with an RCA cleaning solution. Thereafter, the inspection is performed and shipped as a final wafer product. Note that the wafer that has undergone the mirror polishing step 27 may be temporarily stored in a storage solution as necessary before being subjected to the cleaning step 28. That is, the wafer that has undergone the mirror polishing step 27 is sent to the final cleaning step, which is the next step, but is temporarily stored in the storage liquid during a waiting time (such as time required for conveyance) until it is sent to the cleaning step. There is a case. This is because if the wafer is left in the atmosphere, the polishing liquid dries and adheres to the surface of the wafer, making it difficult to remove in the cleaning process. Examples of the storage solution include an aqueous solution containing a chelating agent such as citric acid.

  The sample inspection step 29 includes a step of calculating a colloidal silica adhesion amount from impurities contained in the silica by a particle detection device. As described above, since the polishing material used for finally polishing a semiconductor wafer includes silica fine particles containing impurities, the impurities of the silica fine particles are caused to cause bright spot defects (Light Point Defect) on the surface of the wafer. : LPD).

  An aqueous solution in which 3% by weight of sodium hydroxide is added as an alkaline catalyst, 2% by weight of trisodium citrate is added as a dispersant, and yttrium oxide, manganese dioxide, and zinc chloride are dissolved as impurities in an amount of 1% by weight. Tetraethyl silicate was added to the above, and the above-obtained polishing liquid was produced.

  Using this polishing liquid, the glass materials shown in Table 1 were finally polished to produce five glass substrates for hard disk drives as precision parts.

  The glass substrate is in a stage where a melting process, a grinding process, a polishing process, and a cleaning process are performed in steps 1 to 4 in FIG. In the polishing step, the glass substrate was finally polished with a polishing liquid containing yttrium manufactured by the manufacturing method of the embodiment, and washed and dried.

  Next, a sample inspection process was performed. In this sample inspection process, in order to confirm the effect of a polishing liquid mainly composed of silica fine particles containing impurities, a defect in which a glass substrate after cleaning is inspected with an optical surface analyzer (OSA) and a defect site is counted. A counting step was performed in advance, followed by a lysis step and a quantification step. In the defect counting step, Candela 6300 manufactured by KLA-Tencor Corporation was used as the OSA, and five glass substrates were inspected. The defect counts were as shown in Table 2, respectively.

  Next, as a dissolution step, these five glass substrates were each immersed in an aqueous solution of 3N sulfuric acid (using ultrapure water) with 0.1% hydrofluoric acid, and heated to 80 ° C. to dissolve the colloidal silica. . Thereafter, as a quantitative step, the amount of yttrium was measured with a high-frequency inductively coupled plasma mass spectrometer (7700 s) manufactured by Agilent Technologies, and the colloidal silica adhering to the glass substrate was quantitatively determined from the calibration curve. The results are shown in Table 3.

  As is clear from Table 3, it was found that even if the glass substrate had no difference in the evaluation of the deposits by OSA so far, the detected amount was different by detecting the impurities.

  As described above, the adhesion of colloidal silica that has not been detected so far can be quantitatively detected, which can contribute to the improvement of the quality of precision parts.

  An aqueous solution in which 3% by weight of sodium hydroxide is added as an alkaline catalyst, 2% by weight of trisodium citrate is added as a dispersant, and yttrium oxide, manganese dioxide, and zinc chloride are dissolved as impurities in an amount of 1% by weight. Tetraethyl silicate was added to the above, and the above-obtained polishing liquid was produced.

Using this polishing liquid, a silicon wafer substrate (diameter 200 mm) as a precision part on which a SiO ₂ oxide film used for a semiconductor device was formed was manufactured. The silicon wafer substrate is polished with the polishing liquid according to the above-described embodiment through steps 20 to 27 in FIG.

  After polishing the silicon wafer substrate after RCA cleaning and drying, three sample products were evaluated with a particle detector.

  As is apparent from Table 4, even in the case of silica fine particles remaining on the silicon wafer substrate that have been difficult to detect until now, in this embodiment, impurities contained in the silica fine particles of the polishing liquid are detected. Thus, it is possible to determine the quality of the silicon wafer substrate effectively.

  The above-described embodiment is merely a preferred specific example of the present invention, and the present invention is not limited to the above-described embodiment. It goes without saying that various modifications are possible within the scope of the claims of the present invention.

Claims (13)

It remains in the precision part that has undergone a polishing process for polishing a precision part based on silicon dioxide with a polishing liquid containing silica fine particles containing impurities in the composition, and a cleaning process for cleaning the precision part after the polishing process. A method for measuring silica fine particles for measuring silica fine particles,
A dissolution step of dissolving the surface of the precision part with a solution after the cleaning step;
And a quantitative step of quantifying the silica fine particles from the amount of impurities in the solution that has undergone the dissolution step. It remains in the precision part that has undergone a polishing process for polishing a precision part based on silicon dioxide with a polishing liquid containing silica fine particles containing impurities in the composition, and a cleaning process for cleaning the precision part after the polishing process. A method for measuring silica fine particles for measuring silica fine particles,
A method for measuring silica fine particles, comprising: a defect counting step for optically counting defect sites on the surface of the precision component after the cleaning step and detecting the impurities contained in the silica fine particles. . In the measuring method of the silica fine particles according to claim 2,
In the defect counting step, a bright spot defect is detected by scanning the surface of the semiconductor wafer as the precision component with a laser beam and measuring the light scattering intensity. In the measuring method of the silica fine particles according to any one of claims 1 to 3,
The impurities include titanium, vanadium, zinc, gallium, germanium, rubidium, strontium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, indium, tin, antimony, tellurium, cesium, barium, hafnium, tantalum, tungsten, A method for measuring fine silica particles, which is an element selected from the group consisting of rhenium, iridium, platinum, gold, lead, bismuth, and rare earth elements. In the measuring method of the silica fine particles according to any one of claims 1 to 4,
The method for measuring silica fine particles, wherein the silica fine particles are colloidal silica. In the measuring method of the silica fine particles according to any one of claims 1 to 5,
The silica fine particles have a particle size of 1 nm to 100 nm. In the measuring method of the silica fine particles according to any one of claims 1 to 6,
Content of the said impurity is the range from 1 ppm to 10,000 ppm of total mass. The measuring method of the silica particle characterized by the above-mentioned. In the measuring method of the silica fine particles according to any one of claims 1 to 7,
The method for measuring silica fine particles, wherein the polishing step is a final polishing step of the precision part. In the measuring method of the silica fine particles according to any one of claims 1 to 8,
Elements as the impurities are titanium, vanadium, gallium, germanium, rubidium, strontium, zirconium, niobium, molybdenum, rhodium, palladium, silver, indium, tin, cesium, barium, hafnium, tantalum, tungsten, rhenium, lead, bismuth. And a method for measuring silica fine particles, wherein the silica fine particles are selected from rare earth elements. In the measuring method of the silica fine particles according to any one of claims 1 to 9,
The element as the impurity is selected from rare earth elements. A method for measuring silica fine particles, wherein: In the measuring method of the silica fine particles according to any one of claims 1 to 8,
The element as the impurity is at least one of ruthenium, rhodium, and palladium. In the measuring method of the silica fine particles according to any one of claims 1 to 8,
The element as the impurity is at least one of germanium, strontium, and tellurium. In the measuring method of the silica fine particles according to any one of claims 1 to 8,
The element as the impurity is at least one of tungsten, tantalum, molybdenum, niobium, and zirconium.

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