TWI680298B - Analytical method for analyzing silicon/silicon carbide mixed ingot - Google Patents

Abstract

A method for analyzing a silicon / silicon carbide mixed ingot includes the steps of: providing a silicon / silicon carbide mixed ingot; crushing a silicon / silicon carbide mixed ingot to obtain a processed silicon / silicon carbide mixed sample; and A first portion of the treated silicon / silicon carbide mixed sample was subjected to an acid-soluble gravimetric analysis to obtain a silicon carbide content value; a second portion of the treated silicon / silicon carbide mixed sample was subjected to A gas volume method analysis to obtain a metal silicon content value; a third total sample of the processed silicon / silicon carbide mixed sample is subjected to a free total silicon content value analysis to obtain a free total silicon content value; and Subtract the free silicon content value from the metallic silicon content value to obtain a silicon dioxide content value.

Description

Analytical method of silicon / silicon carbide mixed ingots

The invention relates to a method for analyzing silicon / silicon carbide mixed ingots, and more particularly to a method for analyzing silicon / silicon carbide mixed ingots made from silicon sludge resources in the solar industry.

In the existing silicon / silicon carbide analysis method, silicon carbide is the first analysis of the total carbon content of the sample, and the sample is placed in a high-temperature furnace at 850 ° C. The loss on ignition (LOI) is defined as the free carbon content and the total carbon content. Subtracting the free carbon content to obtain a fixed carbon content, the silicon carbide content can be obtained from molecular weight conversion.

However, when the free carbon is lost in a high-temperature furnace, the weight of the sample after burning (for example, 1.7048 g) will be greater than the weight of the sample before burning (for example, 1.8202 g) (that is, LOI <0). (Pure silicon) oxidizes at high temperatures causing weight gain. Therefore, the existing silicon carbide analysis methods are not applicable to silicon / silicon carbide mixed ingot type materials, and are only applicable to the analysis of high-purity silicon carbide samples.

In addition, the existing metal silicon / silicon dioxide is analyzed by potassium titanosilicate precipitation titration method, but when the particle size of the metal silicon powder in the sample is small, the metal silicon powder oxidizes at a fast rate in the aqueous solution, which will cause the metal silicon / silicon dioxide. Deviations in silica analysis.

Therefore, it is necessary to provide a method for analyzing silicon / silicon carbide mixed ingots to solve the problems existing in conventional technology.

The main purpose of the present invention is to provide a method that uses acid gravimetric analysis to obtain a silicon carbide content value, thereby improving conventional methods that cannot accurately analyze the silicon carbide content value of a silicon / silicon carbide mixed ingot type material.

The secondary purpose of the present invention is to analyze by gas volume method in order to obtain a Metal silicon content value, and thus improve the conventional method cannot accurately analyze the metal silicon content value of silicon / silicon carbide mixed ingot type materials.

In order to achieve the above object, the present invention provides a method for analyzing a silicon / silicon carbide mixed ingot, which includes the steps of: providing a silicon / silicon carbide mixed ingot; and crushing a silicon / silicon carbide mixed ingot to obtain a processed Silicon / silicon carbide mixed sample; and a first portion of the treated silicon / silicon carbide mixed sample is subjected to an acid-soluble gravimetric analysis to obtain a silicon carbide content value; the processed silicon / silicon carbide mixed sample A second part of the sample was analyzed by a gas volumetric method to obtain a metal silicon content value; a third part of the processed silicon / silicon carbide mixed sample was analyzed for a free total silicon content value, To obtain a free total silicon content value; and subtract the metal silicon content value from the free total silicon content value to obtain a silicon dioxide content value.

In one embodiment of the present invention, the performing the acid-soluble gravimetric analysis is: putting the first part of the sample in a mixed acid solution and mixing, and then reacting the first part of the sample after the mixed acid solution is reacted After filtering, a filter residue is obtained, and the filter residue is weighed to obtain the silicon carbide content value.

In one embodiment of the present invention, the mixed acid solution is a mixed solution of hydrochloric acid, nitric acid and hydrofluoric acid.

In one embodiment of the present invention, the silicon / silicon carbide mixed ingot includes a silicon powder, a silicon carbide, and a binder. The silicon powder has an average particle size of less than 5 microns.

In one embodiment of the present invention, performing the gas volumetric method analysis is: placing the second part of the sample in an aqueous sodium hydroxide solution to oxidize a metal silicon in the second part of the sample to produce A hydrogen gas, and a content value of the hydrogen gas is used to obtain the metal silicon content value.

In one embodiment of the present invention, a method for analyzing a silicon / silicon carbide mixed ingot is provided. The method described above is used to separately determine the silicon carbide content value or the metallic silicon content value.

The invention also provides a method for analyzing a silicon / silicon carbide mixed ingot, which includes the steps of: providing a silicon / silicon carbide mixed ingot; and crushing a silicon / silicon carbide mixed ingot to obtain a treated silicon / silicon carbide mixed ingot. Sample; and a first portion of the treated silicon / silicon carbide mixed sample is subjected to an acid gravimetric analysis to obtain a silicon carbide content value; a second to the treated silicon / silicon carbide mixed sample For a part of the sample, a free total silicon content analysis is performed to obtain a free total silicon content value; and a third part of the processed silicon / silicon carbide mixed sample is subjected to a Analysis of main metal content, conversion to obtain a main metal element oxygen contribution and a total oxygen content value; the total oxygen content value and the main metal element oxygen contribution value to obtain a silicon dioxide content value; and via the free total The silicon content value and the silicon dioxide content value obtain a metal silicon content value.

In one embodiment of the present invention, the performing the acid-soluble gravimetric analysis is: putting the first part of the sample in a mixed acid solution and mixing, and then reacting the first part of the sample after the mixed acid solution is reacted After filtering, a filter residue is obtained, and the filter residue is weighed to obtain the silicon carbide content value.

In one embodiment of the present invention, the mixed acid solution is a mixed solution of hydrochloric acid, nitric acid and hydrofluoric acid.

In one embodiment of the present invention, the silicon / silicon carbide mixed ingot includes a silicon powder, a silicon carbide, and a binder. The silicon powder has an average particle size of less than 5 microns.

S11 ~ S16‧‧‧step

S21 ~ S27‧‧‧ steps

FIG. 1 is a schematic flowchart of a first embodiment of the present invention.

FIG. 2 is a schematic flowchart of a second embodiment of the present invention.

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, the following describes the preferred embodiments of the present invention and the accompanying drawings in detail, as follows. Furthermore, the directional terms mentioned in the present invention include, for example, top, bottom, top, bottom, front, back, left, right, inside, outside, side, periphery, center, horizontal, horizontal, vertical, vertical, axial, The radial direction, the uppermost layer, or the lowermost layer, etc., are only directions referring to the attached drawings. Therefore, the directional terms used are for explaining and understanding the present invention, but not for limiting the present invention.

The term "metal silicon" as used herein refers to pure silicon, which is not bonded to other elements (such as oxygen and carbon). The source can be silicon wafers produced by cutting or grinding in the solar or semiconductor industry.

The term "free total silicon" as used herein refers to silicon that can be dissolved in a mixed acid solution in a silicon / silicon carbide mixed ingot, digested by heating in a hydrofluoric acid, nitric acid, and hydrochloric acid solution, and potassium salts are added to produce potassium fluorosilicate precipitation (Equation 1 ), After filtration, potassium fluorosilicate is dissolved in water to generate hydrofluoric acid (formula 2), and the total free silicon content is calculated by titration with sodium hydroxide (formula 2).

_{^{Si + 4NO 3 - + 6F -}} + 8H + + 2K + → K 2 SiF 6 ↓ (s) + 4NO 2 (g) + 4H 2 O ( Formula 1)

K ₂ SiF ₆ (s) + 3H ₂ O → H ₂ SiO ₃ + 4HF + 2KF (Equation 2)

HF + NaOH → NaF + H ₂ O (Equation 3)

Referring to FIG. 1, a first embodiment of the present invention provides a method for analyzing a silicon / silicon carbide mixed ingot, which includes the steps of: providing a silicon / silicon carbide mixed ingot; and crushing a silicon / silicon carbide mixed ingot. Processing to obtain a processed silicon / silicon carbide mixed sample; and performing a acid-gravimetric analysis on a first portion of the processed silicon / silicon carbide mixed sample to obtain a silicon carbide content value; A second portion of the processed silicon / silicon carbide mixed sample was analyzed by a gas volumetric method to obtain a metallic silicon content value; a third portion of the processed silicon / silicon carbide mixed sample was subjected to a The free total silicon content value is analyzed to obtain a free total silicon content value; and the free total silicon content value is subtracted from the metallic silicon content value to obtain a silicon dioxide content value.

The present invention will be described in detail below using the first figure one by one in the implementation details of the above steps of the first embodiment, corresponding processing equipment and its principle.

Please refer to FIG. 1. The silicon / silicon carbide mixed ingot used in the first embodiment of the present invention is a silicon mud formed by cutting and grinding silicon wafers in the solar energy or semiconductor industry. Silicon / silicon carbide mixed ingot. It is to collect the silicon mud, add a binder, and then press it into the silicon / silicon carbide mixed ingot. The average particle size of the silicon powder in the silicon mud is less than 5 micrometers, for example, about 1 micrometer. When the silicon / silicon carbide mixed ingot was analyzed using a conventional method, the analysis result was significantly different from the actual value. After the silicon / silicon carbide mixed ingot used in this embodiment is crushed, the composition of the silicon / silicon carbide mixed ingot using the method of the present invention is shown in Table 1 below:

Please refer to FIG. 1, after the silicon / silicon carbide mixed ingot is crushed to obtain a processed silicon / silicon carbide mixed sample, wherein the particle size of the processed silicon / silicon carbide mixed sample is less than 149 microns. Take the processed silicon / silicon carbide mixed sample and take a first part of the sample for an acid-soluble gravimetric analysis. The said acid-soluble gravimetric analysis is as follows: putting the first part of the sample into a mixed acid solution After mixing, the first part of the sample after reacting with the mixed acid solution is filtered to obtain a filter residue, and the filter residue is weighed to obtain a silicon carbide content value. In this embodiment, the first part of the sample is placed in a mixed solution of hydrochloric acid, nitric acid and hydrofluoric acid for 50 minutes, and then cooled and filtered. The insoluble matter obtained after filtering is placed in a platinum crucible together with filter paper and heated for 780 It is ashed to 800 ° C, and after constant weight, the silicon carbide content value is obtained. As described above, the silicon carbide content of the present invention is about 44% to 47% by weight, and the metal silicon content is about 21% to 24% by weight, compared with the use of conventional carbon. Analytical method (CNS9439). The acid gravimetric method used in this example is simpler and faster than the conventional carbon method.

Please refer to FIG. 1, and perform a gas volumetric analysis on a second part of the processed silicon / silicon carbide mixed sample to obtain a metal silicon content value. The gas volume analysis is performed as follows: the second part of the sample is placed in an aqueous solution of sodium hydroxide (for example, 250 g / liter), and the solution is boiled for 90 minutes by heating to make the second part of the sample A metal silicon is oxidized to generate a hydrogen gas, and a content value of the hydrogen gas is used to obtain the metal silicon content value. The second part of the sample is heated under reflux in the sodium hydroxide aqueous solution for 1.5 hours. The metal silicon undergoes a redox reaction to generate hydrogen and silicate, while the silicon dioxide undergoes only a hydrolysis reaction. measured in terms of the volume of hydrogen to metal silicon content value by the perfect gas equation, the following reaction formula (formula 4) and (formula ^{5): Si (s) + 4OH -} → SiO 4 4- (aq) + 2H ₂ (g) (Eq. 4)

^{_{SiO 2 (s) + 4OH -}} → SiO 4 4- (aq) + 2H 2 O ( Equation 5)

The present invention uses the gas volume method to analyze the metal silicon content value and uses a standard sample to simulate a silicon / silicon carbide mixed sample. The analysis results are shown in Table 2 below. The results show that the method of the present invention is indeed feasible.

Furthermore, when the binder (for example, bentonite) is analyzed under the same analysis conditions, no hydrogen is generated, so the binder does not interfere with the analysis result.

Please refer to FIG. 1 to perform a free total silicon content analysis on a third portion of the processed silicon / silicon carbide mixed sample to obtain a free total silicon content value; and subtract the free total silicon content value Remove the metal silicon content value to obtain the silicon dioxide content value. The free total silicon content in the silicon / silicon carbide mixed ingot is mainly the metal silicon content and the silicon dioxide content. The silicon dioxide content can be obtained by subtracting the metal silicon content value from the free total silicon content value. value.

The above-mentioned analysis method of the silicon / silicon carbide mixed ingot of the present invention can be used alone to determine the silicon carbide content value or the metallic silicon content value.

Referring to FIG. 2, a second embodiment of the present invention provides a method for analyzing a silicon / silicon carbide mixed ingot, which includes the steps of: providing a silicon / silicon carbide mixed ingot; and crushing a silicon / silicon carbide mixed ingot. Processing to obtain a processed silicon / silicon carbide mixed sample; and performing a acid-gravimetric analysis on a first portion of the processed silicon / silicon carbide mixed sample to obtain a silicon carbide content value; A second portion of the processed silicon / silicon carbide mixed sample is subjected to a free total silicon content analysis to obtain a free total silicon content value; and a third portion of the processed silicon / silicon carbide mixed sample is analyzed. The sample is subjected to a main metal content analysis, and converted to obtain a main metal element oxygen contribution amount and a total oxygen content value; the total oxygen content value and the main metal element oxygen contribution value to obtain a silicon dioxide content value; and The free total silicon content value and the silicon dioxide content value obtain a metal silicon content value. The second embodiment of the present invention is different from the first embodiment of the present invention in that the metal silicon content value and the silicon dioxide content value are estimated by an indirect method.

In the present invention, the method and principle of indirect estimation of the metal silicon content value and the silicon dioxide content value in the second embodiment will be described in detail one by one.

Please refer to Figure 2 for the processed silicon / silicon carbide mixed sample. Three main samples were analyzed for the main metal content, and the results are shown in Table 3 below. The total oxygen content does not include the oxygen element contribution in water molecules.

Next, each element (M) in the above Table 3 is converted into its common oxide (MxOy) form, as an example in Table 4 below. For example, after the analysis of the main metal content, the weight percentage of iron (Fe) in the overall sample is 5.07%. When converted to the oxide type, the calculated iron oxide concentration is 7.25% (as shown in Equation 6 below) . The oxygen contribution of iron was 2.17% after being converted by (Expression 7).

Calculated Concentration of Iron Oxide = Analytical Concentration / Molar Fraction of Iron in Iron Trioxide (Equation 6)

Oxygen contribution of iron = calculated iron oxide concentration-iron analytical concentration (Equation 7)

Next, the estimated value of silicon dioxide can be calculated by (Expression 8 below) and the estimated value of the estimated value of metal silicon can be calculated by (Expression 9).

Estimated value of silicon dioxide = (total oxygen content value-main metal oxygen contribution) * 60.1 / 32 (Eq. 8)

Estimated Silicon Metal = Free Total Silicon Content-(Estimated Silicon Dioxide * 28.1 / 60.1) (Eq. 9)

To sum up, the present invention can regenerate the silicon / silicon carbide mixed ingot made from a silicon sludge formed by cutting and grinding of silicon wafers in the solar energy or semiconductor industry, and solve the analysis results when using conventional methods for analysis. There is a significant deviation from the actual value. The invention can solve the error of analysis result caused by the small particle diameter of the silicon metal which is easily oxidized to silicon dioxide. Furthermore, the method of analyzing the silicon carbide content by the acid-soluble gravimetric method is simpler and faster than the conventional carbon analysis method.

Although the present invention has been disclosed in a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. The scope of protection shall be determined by the scope of the attached patent application.

Claims (10)

A method for analyzing a silicon / silicon carbide mixed ingot includes the steps of: providing a silicon / silicon carbide mixed ingot; crushing a silicon / silicon carbide mixed ingot to obtain a treated silicon / silicon carbide mixed sample; and A first portion of the treated silicon / silicon carbide mixed sample is subjected to an acid-gravimetric analysis to obtain a silicon carbide content value; a second portion of the treated silicon / silicon carbide mixed sample is Perform a gas volume analysis to obtain a metal silicon content value; perform a free total silicon content analysis on a third portion of the treated silicon / silicon carbide mixed sample to obtain a free total silicon content value; And subtracting the metal silicon content value from the free total silicon content value to obtain a silicon dioxide content value. The method for analyzing a silicon / silicon carbide mixed ingot according to item 1 of the scope of the patent application, wherein the acid-gravimetric analysis is performed as follows: the first part of the sample is mixed in a mixed acid solution, and then the After the reaction of the mixed acid solution, the first part of the sample is filtered to obtain a filter residue, and the filter residue is weighed to obtain the silicon carbide content value. The method for analyzing a silicon / silicon carbide mixed ingot according to item 2 of the scope of patent application, wherein the mixed acid solution is a mixed solution of hydrochloric acid, nitric acid and hydrofluoric acid. The method for analyzing a silicon / silicon carbide mixed ingot according to item 1 of the patent application scope, wherein the silicon / silicon carbide mixed ingot includes a silicon powder, a silicon carbide, and a binder, and the silicon powder has an average particle size of less than 5 Microns. The analysis method of the silicon / silicon carbide mixed ingot according to item 1 of the scope of the patent application, wherein the gas volume analysis is performed as follows: placing the second part of the sample in an aqueous sodium hydroxide solution, A metal silicon in the second part of the sample is oxidized to generate a hydrogen gas, and a content value of the hydrogen gas is used to obtain the metal silicon content value. A method for analyzing a silicon / silicon carbide mixed ingot, using the method described in any one of claims 1 to 5 of the patent application scope to separately determine the silicon carbide content value or the metallic silicon content value. A method for analyzing a silicon / silicon carbide mixed ingot includes the steps of: providing a silicon / silicon carbide mixed ingot; crushing a silicon / silicon carbide mixed ingot to obtain a treated silicon / silicon carbide mixed sample; and A first portion of the treated silicon / silicon carbide mixed sample is subjected to an acid-gravimetric analysis to obtain a silicon carbide content value; a second portion of the treated silicon / silicon carbide mixed sample is Perform a free total silicon content analysis to obtain a free total silicon content value; and perform a main metal content analysis on a third portion of the treated silicon / silicon carbide mixed sample to convert to obtain a main metal element Oxygen contribution and a total oxygen content value; a silicon dioxide content value is obtained from the total oxygen content value and the main metal element oxygen contribution value; and a metal is obtained from the free total silicon content value and the silicon dioxide content value Silicon content value. The method for analyzing a silicon / silicon carbide mixed ingot according to item 7 in the scope of the patent application, wherein the acid-gravimetric analysis is performed as follows: the first part of the sample is mixed in a mixed acid solution, and then the After the reaction of the mixed acid solution, the first part of the sample is filtered to obtain a filter residue, and the filter residue is weighed to obtain the silicon carbide content value. The method for analyzing a silicon / silicon carbide mixed ingot according to item 7 of the scope of the patent application, wherein the mixed acid solution is a mixed solution of hydrochloric acid, nitric acid and hydrofluoric acid. The method for analyzing a silicon / silicon carbide mixed ingot according to item 7 of the scope of the patent application, wherein the silicon / silicon carbide mixed ingot includes a silicon powder, a silicon carbide, and a binder, and the silicon powder has an average particle size of less than 5 Microns.