A method for preparing electronic-grade n-hexane for semiconductor cleaning and its application.

Abstract

This invention relates to the field of n-hexane preparation technology, specifically to a method for preparing electronic-grade n-hexane for semiconductor cleaning and its application. The method includes the following steps: Raw material pretreatment: Industrial-grade n-hexane is taken, neutralized with sodium hydroxide solution, allowed to stand and separate into layers, the oil phase is collected, washed with deionized water, dried with a desiccant, allowed to stand, and then filtered to obtain pretreated n-hexane. This invention constructs a core process system of raw material pretreatment – ​​atmospheric pressure distillation – composite adsorption – ultra-clean filtration, and can be further combined with improved schemes such as vacuum distillation and oxidation-adsorption combined treatment to achieve synergistic and deep removal of various impurities such as moisture, aromatics, metal ions, and unsaturated hydrocarbons from n-hexane.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of n-hexane preparation, in particular to a preparation method and application of electronic-grade n-hexane for semiconductor cleaning. BACKGROUND

[0002] Electronic-grade n-hexane is a key cleaning reagent in the field of semiconductor manufacturing, and its purity and impurity content directly determine the cleaning effect of semiconductor wafers, thereby affecting the performance stability and production yield of subsequent semiconductor devices. In particular, in the development process of advanced semiconductor processes, more stringent requirements are put forward for the purity control, impurity type and content limitation of electronic-grade n-hexane.

[0003] However, the existing electronic-grade n-hexane preparation technology and products have many technical limitations. Traditional preparation processes rely on a single adsorbent for impurity treatment, which is difficult to achieve simultaneous and efficient removal of multiple impurities such as water, aromatic hydrocarbons and metal ions, resulting in high residual impurity content in the product, which cannot meet the demand for low-impurity environment in high-precision semiconductor cleaning. The design of conventional rectification process parameters is unreasonable, which is prone to problems such as high energy consumption or n-hexane thermal cracking, thereby increasing production costs and possibly introducing new impurities due to cracking, thereby reducing product purity. The existing process for removing unsaturated hydrocarbons, such as Pd / C catalytic hydrogenation method, not only requires the use of high-cost noble metal catalysts, but also may generate n-hexane isomers, further affecting product quality and increasing the difficulty of subsequent purification. Fourthly, the commercially available electronic-grade n-hexane generally has high content of metal ions, water and aromatic hydrocarbons, which can only be adapted to low-precision semiconductor processes and cannot meet the stringent standards of cleaning reagents for advanced processes. In addition, the adaptability of some preparation processes to different amounts of raw materials is poor, which is prone to fluctuations in product performance due to changes in raw material quantity, which is not conducive to large-scale industrial application. These defects of the existing technology seriously restrict the application of electronic-grade n-hexane in the field of advanced semiconductor manufacturing, and new preparation methods are urgently needed to solve the above problems. SUMMARY

[0004] The primary object of the present application is to provide a preparation method and application of electronic-grade n-hexane for semiconductor cleaning.

[0005] A further object of the present application is to provide a preparation method of electronic-grade n-hexane for semiconductor cleaning, which comprises the following steps:

[0006] (1) Raw material pretreatment: take industrial-grade n-hexane, add sodium hydroxide solution for neutralization, take the oil phase after standing and layering, wash with deionized water, then add a drying agent for drying, stand and filter to obtain pretreated n-hexane;

[0007] (2) Atmospheric distillation: send the pretreated n-hexane into a rectifying column, control the column top temperature and reflux ratio, collect the column top fraction to obtain crude n-hexane;

[0008] (3) Composite adsorption: passing crude n-hexane through an adsorption column filled with adsorbent at a set flow rate, and controlling the adsorption temperature to obtain adsorbed n-hexane; the adsorbent at least comprises molecular sieve and activated alumina;

[0009] (4) Ultra-clean filtration: filtering the adsorbed n-hexane through a filter core to obtain electronic-grade n-hexane; the filter core is made of polytetrafluoroethylene or polypropylene.

[0010] Preferably, in step (1), the volume fraction of the sodium hydroxide solution is 8%-12%, the amount is 3%-8% of the volume of the raw material, the pH of the water phase after neutralization is 6.8-7.2; the resistivity of the deionized water is 18.2 Mohm·cm , the number of water washing times is 2-4, and the amount of water used each time is 8%-15% of the volume of the raw material; the drying agent is anhydrous magnesium sulfate or anhydrous sodium sulfate, and the amount is 0.3%-0.8% of the mass of the raw material; the moisture content of the pretreated n-hexane after drying is ≤60 ppm.

[0011] Preferably, in step (2), the rectifying column is a packed rectifying column or a plate rectifying column, and the number of plates is 25-35; the overhead temperature is 66-70℃, and the reflux ratio is 2:1-4:1.

[0012] Preferably, in step (3), the mass ratio of the molecular sieve to the activated alumina is 1:1-1:2; the molecular sieve is 3A molecular sieve, 4A molecular sieve or 5A molecular sieve; the specific surface area of the activated alumina is ≥280 m 2 / g; the height of the adsorption column is 40-60 cm, the flow rate is 0.8-1.2 mL / min, and the adsorption temperature is 35-45℃.

[0013] Preferably, in step (3), the adsorbent further comprises metal chelating resin, and the mass ratio of the molecular sieve, the activated alumina and the metal chelating resin is 1:1:1-3:3:1; the metal chelating resin is of amino phosphonic acid type, carboxylic acid type or imine diacetic acid type; the adsorption temperature is adjusted to 45-55℃, and the flow rate is adjusted to 0.6-1.0 mL / min.

[0014] Preferably, after the atmospheric pressure rectification in step (2), a vacuum rectification step is further included: passing the crude n-hexane into a vacuum rectifying column, controlling the vacuum degree, the overhead temperature and the reflux ratio, and collecting the overhead fraction; the vacuum rectifying column is a plate column or a packed column, and the number of plates is 35-45; the vacuum degree is 0.092-0.098 MPa, the overhead temperature is 42-48℃, and the reflux ratio is 4:1-6:1.

[0015] Preferably, the reduced pressure rectification further comprises an oxidation-adsorption combined treatment step: the reduced pressure rectification fraction is subjected to ultraviolet oxidation treatment, and the oxidized material is directly introduced into the composite adsorption column of step (3); the wavelength of the ultraviolet oxidation is 240-250 nm, the power is 80-120 W, the oxygen volume ratio is 0.3%-0.7%, the reaction temperature is 32-38 DEG C, and the reaction time is 25-35 min.

[0016] Preferably, the ultraviolet oxidation is replaced by ultraviolet synergistic hydrogen peroxide oxidation; the mass ratio of hydrogen peroxide to material is 0.2%-0.5%.

[0017] Preferably, the ultraviolet oxidation is replaced by plasma oxidation; the power of the plasma oxidation equipment is 50-80 W, the oxygen volume ratio is 0.3%-0.7%, the reaction temperature is 32-38 DEG C, and the reaction time is 30-35 min.

[0018] The application also provides an application of the electronic-grade n-hexane prepared by the above method in semiconductor cleaning.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] 1. The application realizes the synergistic deep removal of water, aromatic hydrocarbons, metal ions, unsaturated hydrocarbons and other impurities in n-hexane by constructing a core process system of raw material pretreatment-normal pressure rectification-composite adsorption-ultra-clean filtration, and further combining improved schemes such as reduced pressure rectification and oxidation-adsorption combined treatment. In the composite adsorption step, a combination of molecular sieves, modified adsorbents and chelating resins is innovatively adopted, and the synergistic effect of each adsorbent material is utilized to effectively break through the limitations of traditional single adsorbents and greatly reduce the content of metal ions, aromatic hydrocarbons and water in the product; the oxidation-adsorption combined treatment can deeply remove unsaturated hydrocarbons and avoid the generation of n-hexane isomers through ultraviolet or plasma oxidation technology, further improving the product purity and meeting the stringent requirements of advanced semiconductor processes for high-purity cleaning reagents.

[0021] 2. The application can flexibly adapt to different amounts of raw materials by accurately optimizing the key parameters of each process step, and only needs to adjust the related process parameters simultaneously to stably control the impurity removal efficiency when the amount of raw material changes, thereby avoiding product performance fluctuations caused by changes in the amount of raw material. At the same time, the electronic-grade n-hexane prepared by the application can maintain the purity and key impurity content within the range required by advanced processes after long-term storage, and the process stability and product storage stability are excellent, providing reliable protection for large-scale industrial application.

[0022] 3. This invention optimizes the vacuum distillation parameters in the distillation step. By controlling the appropriate vacuum level, column top temperature and reflux ratio, it cleverly balances the low boiling point requirement of n-hexane with the low cracking risk. This avoids the problem of excessive energy consumption under conventional low vacuum conditions and reduces the risk of easy cracking of n-hexane at high temperatures, effectively reducing process energy consumption. At the same time, it reduces the possibility of introducing new impurities due to cracking, significantly improving process safety and economy.

[0023] 4. The electronic-grade n-hexane prepared by this invention, when used for semiconductor wafer cleaning, can efficiently remove particles, organic contaminants, and residual metal ions from the wafer surface, significantly reducing leakage current in semiconductor devices after cleaning and greatly improving device yield. Compared to commercially available products and products prepared using traditional processes, the product of this invention can be stably adapted to higher-precision advanced semiconductor processes, overcoming the limitation of existing products that can only be adapted to lower-precision processes. It provides reliable cleaning reagent support for advanced semiconductor manufacturing and has significant industrial application value. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1:

[0026] (1) Raw material pretreatment:

[0027] Take 50L of industrial-grade n-hexane, with an initial purity of 90%, containing 0.1% acidic impurities, 0.3% aromatics, and 60ppm water;

[0028] Add 3% sodium hydroxide solution by volume of the raw material. The mass fraction of this solution is 8%. After neutralization, the pH of the aqueous phase needs to reach 6.8. If the pH is below 8%, the neutralization is incomplete, and if it is above 12%, residual alkali is likely to remain.

[0029] Stirring at 25℃ and 180 rpm for 25 minutes ensures sufficient contact between the alkali solution and the raw materials, with a contact efficiency of 95%.

[0030] After settling and separating, the oil phase is taken and its resistivity is used. The material was washed twice with deionized water, with each wash using 8% of the raw material volume. After washing, the pH of the aqueous phase reached 6.8.

[0031] Add 0.3% anhydrous magnesium sulfate by weight of the raw material. Anhydrous sodium sulfate can also meet the drying requirements. The moisture content after drying should be ≤60ppm. After standing for 1.5h, filter to obtain pretreated n-hexane with a moisture content of 45ppm.

[0032] (2) Normal pressure rectification:

[0033] The pretreated n-hexane is fed into a packed rectification column with 25 plates, which can ensure that the residual light component pentane is ≤0.1% and the residual heavy component heptane is ≤0.15%;

[0034] The overhead temperature is controlled at 66°C, which is the lower limit of the boiling point of n-hexane with a deviation of 1°C. A deviation greater than this will cause the purity to decrease by ≥0.3%. The reflux ratio is controlled at 2:1. A reflux ratio lower than 2:1 will cause the residual heavy component to exceed the standard, and a reflux ratio higher than 4:1 will increase the energy consumption by ≥30%;

[0035] The overhead fraction is collected to obtain crude n-hexane with a purity of 99.2% and 800 ppm of aromatic hydrocarbons.

[0036] (3) Composite adsorption:

[0037] The flow rate is 0.8 mL / min through an adsorption column with a height of 40 cm. A column height lower than 40 cm is prone to breakthrough, and a column height higher than 60 cm has excessive resistance.

[0038] The column is filled with 3A molecular sieve and activated alumina at a mass ratio of 1:1. The 3A molecular sieve can be replaced by 4A molecular sieve, which needs to have a water adsorption capacity of ≥20%. The activated alumina has a specific surface area of 280 m² / g and needs to have an aromatic hydrocarbon adsorption capacity of ≥15 mg / g.

[0039] The adsorption temperature is controlled at 35°C. A temperature lower than 35°C will cause the residual water adsorption to be ≥12 ppm, and a temperature higher than 45°C will increase the risk of aromatic hydrocarbon desorption.

[0040] The obtained n-hexane after adsorption has a water content of 10 ppm and an aromatic hydrocarbon content of 200 ppm.

[0041] (4) Ultra-clean filtration:

[0042] The n-hexane is filtered through a 0.08 μm polytetrafluoroethylene filter element. The filter element pore size needs to meet the requirement that the number of particles with a size of >0.5 μm is ≤5 per mL. The polytetrafluoroethylene filter element can be replaced by a polypropylene filter element.

[0043] The obtained electronic-grade n-hexane product 1 has a purity of 99.85% and a metal ion content of 10 ppb.

[0044] Example 2:

[0045] (1) Raw material pretreatment:

[0046] 100 L of industrial-grade n-hexane is taken, which has an initial purity of 95% and contains 0.3% of acidic impurities, 0.5% of aromatic hydrocarbons, and 80 ppm of water.

[0047] Add 5% of the volume of the raw material sodium hydroxide solution with a mass fraction of 10%, and the pH of the water phase after neutralization is 7.0. If the neutralization is less than 8%, it is not complete, and if it is higher than 12%, alkali residues are likely to remain;

[0048] Stir at 30°C and 200 rpm for 30 min. This stirring rate can ensure that the alkali solution and the raw material are in full contact, and the contact efficiency is 98%;

[0049] After standing and layering, take the oil phase, and wash it with deionized water with a resistivity of 18.2 MΩ·cm for 3 times, with each time using 10% of the volume of the raw material. After washing, the pH of the water phase is 7.0.

[0050] Add 0.5% of the mass of the raw material anhydrous sodium sulfate, or anhydrous magnesium sulfate, which can also meet the drying requirements. After drying, the water content should be ≤60 ppm. After standing for 2 h, filter to obtain pretreated n-hexane with a water content of 40 ppm.

[0051] (2) Atmospheric distillation:

[0052] Send the pretreated n-hexane into a plate distillation column with 30 trays. This number of trays can ensure that the light component pentane residue is ≤0.1% and the heavy component heptane residue is ≤0.15%.

[0053] Control the overhead temperature at 68°C, which is the standard boiling point of n-hexane. If the deviation is too large, the purity will decrease by ≥0.3%. Control the reflux ratio at 3:1. If the reflux ratio is lower than 2:1, the heavy component residue will exceed the standard, and if it is higher than 4:1, the energy consumption will increase by ≥30%.

[0054] Collect the overhead fraction to obtain crude n-hexane with a purity of 99.5% and an aromatic hydrocarbon content of 750 ppm.

[0055] (3) Composite adsorption:

[0056] Pass through a 50 cm high adsorption column at a flow rate of 1.0 mL / min. If the column height is lower than 40 cm, it is easy to penetrate, and if it is higher than 60 cm, the resistance is too large.

[0057] Fill the column with 4A molecular sieve and activated alumina at a mass ratio of 1:1.5. The 4A molecular sieve can be replaced by 3A molecular sieve, which needs to have a water adsorption capacity of ≥20%. The activated alumina has a specific surface area of 300 m 2 / g, and needs to have an aromatic hydrocarbon adsorption capacity of ≥15 mg / g.

[0058] Control the adsorption temperature at 40°C. If the temperature is lower than 35°C, the water adsorption residue will be ≥12 ppm, and if it is higher than 45°C, the risk of aromatic hydrocarbon desorption will increase.

[0059] Obtain the adsorbed n-hexane, which has a water content of 8 ppm and an aromatic hydrocarbon content of 180 ppm.

[0060] (4) Ultra-clean filtration: ​

[0061] After filtration through a 0.1μm polypropylene filter cartridge, the filter cartridge pore size must meet the requirement of ≤5 particles > 0.5μm / mL. The polypropylene filter cartridge can be replaced with a polytetrafluoroethylene filter cartridge.

[0062] Electronic-grade n-hexane product 2 was obtained, with a purity of 99.90% and 8 ppb of metal ions.

[0063] Example 3:

[0064] (1) Raw material pretreatment:

[0065] Take 200L of industrial-grade n-hexane, with an initial purity of 97%, containing 0.5% acidic impurities, 0.8% aromatics, and 100ppm water;

[0066] Add 8% sodium hydroxide solution by volume of the raw material. The mass fraction of this solution is 12%. After neutralization, the pH of the aqueous phase needs to reach 7.2. If the pH is below 8%, the neutralization will not be complete, and if it is above 12%, residual alkali will easily remain.

[0067] Stirring at 35℃ and 220 rpm for 35 minutes ensures sufficient contact between the alkali solution and the raw materials, with a contact efficiency of 98%.

[0068] After settling and separating, the oil phase is taken and its resistivity is used. The raw material was washed four times with deionized water, with each wash using 15% of the raw material volume. After washing, the pH of the aqueous phase reached 7.2.

[0069] Add 0.8% anhydrous magnesium sulfate by weight of the raw material. Anhydrous sodium sulfate can also meet the drying requirements. The moisture content after drying should be ≤60ppm. After standing for 2.5 hours, filter to obtain pretreated n-hexane with a moisture content of 35ppm.

[0070] (2) Atmospheric distillation:

[0071] Pretreated n-hexane is fed into a 35-plate distillation column, which ensures that the light component pentane residue is ≤0.1% and the heavy component heptane residue is ≤0.15%.

[0072] The column top temperature is controlled at 70℃, which is the upper limit of the boiling point of n-hexane. A deviation of 1℃ from this temperature will result in a decrease in purity of ≥0.3%. The reflux ratio is controlled at 4:1. A reflux ratio lower than 2:1 will result in excessive residue of heavy components, while a reflux ratio higher than 4:1 will increase energy consumption by ≥30%.

[0073] The top fraction was collected to obtain crude n-hexane with a purity of 99.7% and 850 ppm of aromatics.

[0074] (3) Composite adsorption:

[0075] The flow rate was 1.2 mL / min through a 60 cm high adsorption column. Columns with a height below 40 cm were easily penetrated, while those above 60 cm experienced excessive resistance.

[0076] The 5A molecular sieve with a mass ratio of 1:2 in the column is filled with active alumina, and the 5A molecular sieve can be replaced by 3A / 4A molecular sieve, which needs to meet the water adsorption capacity ≥20%; the specific surface area of the active alumina is 320 m 2 / g, which needs to meet the aromatic adsorption capacity ≥15 mg / g;

[0077] The adsorption temperature is controlled at 45°C, and the water adsorption residue is ≥12 ppm when the temperature is lower than 35°C, and the aromatic desorption risk increases when the temperature is higher than 45°C;

[0078] The obtained n-hexane after adsorption has a water content of 12 ppm and an aromatic content of 220 ppm.

[0079] (4) Ultra-clean filtration:

[0080] The polytetrafluoroethylene filter core is filtered through a 0.12 μm polytetrafluoroethylene filter core, and the filter core aperture needs to meet that the particle size >0.5 μm is ≤5 pieces / mL, and the polytetrafluoroethylene filter core can be replaced by a polypropylene filter core;

[0081] The obtained electronic-grade n-hexane product 3 has a purity of 99.92% and a metal ion content of 6 ppb.

[0082] Example 4:

[0083] (1) On the basis of Example 2, only the composite adsorption step is adjusted, and the remaining steps are completely consistent with Example 2:

[0084] (2) Composite adsorption:

[0085] The 3A molecular sieve, the active alumina with surface-loaded amino groups, and the amino phosphonic acid type metal chelating resin (trade name D401) with a mass ratio of 1:1:1 are filled in the adsorption column;

[0086] The 3A molecular sieve needs to meet the water adsorption ≤8 ppm; the modified active alumina needs to meet the aromatic adsorption ≤100 ppm, and the loading amount of amino groups is 3 wt%, and the adsorption capacity is insufficient when it is lower than 3 wt%, and it is easy to agglomerate when it is higher than 7 wt%; the metal chelating resin needs to meet the metal ion adsorption ≤5 ppb, and the selectivity coefficient of Na + , Fe 3+ is ≥80;

[0087] The adsorption temperature is controlled at 45°C, and the metal ion residue is ≥6 ppb when the temperature is lower than 45°C, and the resin life is shortened by ≥20% when the temperature is higher than 55°C;

[0088] The flow rate is controlled at 0.6 mL / min, which can ensure that the resin and the material are in full contact, and the metal ion penetration risk increases when the flow rate is higher than 1.0 mL / min;

[0089] (3) The remaining steps: same as Example 2;

[0090] Product performance: electronic grade n-hexane product 4 was obtained, with metal ions of 4 ppb, aromatic hydrocarbons of 100 ppm, and moisture of 8 ppm.

[0091] Example 5:

[0092] (1) Based on Example 2, only the composite adsorption step is adjusted, and the remaining steps are completely consistent with Example 2:

[0093] (2) Composite adsorption:

[0094] The adsorption column is filled with 4A molecular sieves, surface-loaded hydroxyl active alumina, and carboxylic acid type metal chelating resin (brand D113) at a mass ratio of 2:2:1;

[0095] The 4A molecular sieves need to meet ≤8 ppm after moisture adsorption; the modified active alumina needs to meet ≤100 ppm after aromatic hydrocarbon adsorption, and the loading amount of amino group needs to be 5wt%, which is insufficient below 3wt% and easy to agglomerate above 7wt%; the metal chelating resin needs to meet ≤5 ppb after metal ion adsorption, and its selectivity coefficient to Na + , Fe 3+ is ≥80;

[0096] The adsorption temperature is controlled at 50°C, and the increase of temperature can enhance the activity of the chelating resin, and the residual metal ions are ≥6 ppb below 45°C, and the service life of the resin is shortened by ≥20% above 55°C;

[0097] The flow rate is controlled at 0.8 mL / min, which can ensure sufficient contact between the resin and the material, and the risk of metal ion breakthrough increases above 1.0 mL / min;

[0098] (3) The remaining steps: same as Example 2;

[0099] Product performance: electronic grade n-hexane product 5 was obtained, with metal ions of 3 ppb, aromatic hydrocarbons of 80 ppm, and moisture of 6 ppm.

[0100] Example 6:

[0101] (1) Based on Example 2, only the composite adsorption step is adjusted, and the remaining steps are completely consistent with Example 2:

[0102] (2) Composite adsorption:

[0103] The adsorption column is filled with 5A molecular sieves, surface-loaded amino modified silica gel, and iminodiacetic acid type metal chelating resin (brand D403) at a mass ratio of 3:3:1;

[0104] 5A molecular sieve needs to meet ≤8 ppm after water adsorption; modified silica gel amino load of 7 wt% needs to meet ≤100 ppm after aromatic adsorption, less than 3 wt% adsorption capacity is insufficient, and more than 7 wt% is prone to agglomeration; metal chelating resin needs to meet ≤5 ppb after metal ion adsorption, and its Na + , Fe 3+ Selectivity coefficient ≥80;

[0105] The adsorption temperature is controlled at 55°C, and the temperature increase can enhance the activity of the chelating resin, and less than 45°C metal ion residue ≥6 ppb, and higher than 55°C resin life is shortened ≥20%;

[0106] The flow rate is controlled at 1.0 mL / min, which can ensure that the resin and the material are in full contact, and higher than 1.0 mL / min metal ion penetration risk increases;

[0107] (3) The remaining steps are the same as in Example 2;

[0108] The product performance: electronic grade n-hexane product 6 is obtained, with metal ion of 2 ppb, aromatic of 70 ppm, and moisture of 4 ppm.

[0109] Example 7:

[0110] (1) On the basis of Example 5, adjust the atmospheric distillation + vacuum distillation step, and the remaining steps are completely consistent with Example 5:

[0111] (2) Atmospheric distillation post-treatment:

[0112] The crude n-hexane obtained in Example 5 is transferred into a 35-plate vacuum distillation column. The column is a plate column, and the number of plates needs to meet the requirement of residual recombinant components ≤0.05%, and the plate column can be replaced by a packed column;

[0113] The vacuum degree is controlled at 0.092 MPa, and the vacuum degree is lower than 0.092 MPa, which can increase the energy consumption by ≥40%, and higher than 0.098 MPa, which can increase the boiling point and cause cracking rate ≥0.03%;

[0114] The overhead temperature is controlled at 42°C, and the thermal cracking rate of n-hexane is ≤0.02% in this temperature range, and higher than 48°C, which can cause a sharp increase in cracking rate;

[0115] The reflux ratio is controlled at 4:1, and the reflux ratio is lower than 4:1, which can reduce the purity to ≤99.95%, and higher than 6:1, which can reduce the production efficiency by ≥25%;

[0116] (3) The remaining steps are the same as in Example 5;

[0117] The product performance: electronic grade n-hexane product 7 is obtained, with purity of 99.96%, thermal cracking impurities of 0.02%, metal ion of 3 ppb, aromatic of 80 ppm, and moisture of 6 ppm.

[0118] Example 8

[0119] (1) On the basis of Example 5, adjust the atmospheric distillation + vacuum distillation step, and the remaining steps are completely consistent with Example 5:

[0120] (2) Atmospheric distillation post-processing:

[0121] The crude n-hexane obtained in Example 5 is transferred into a 40-plate vacuum distillation column, which is a packed column, and the number of plates needs to meet the requirement that the residual heavy components are ≤0.05%, and the packed column can be replaced by a plate column;

[0122] The vacuum degree is controlled at 0.095 MPa, and the energy consumption increases by ≥40% when the vacuum degree is lower than 0.092 MPa, and the boiling point rises to cause cracking rate ≥0.03% when the vacuum degree is higher than 0.098 MPa;

[0123] The overhead temperature is controlled at 45°C, and the thermal cracking rate of n-hexane is ≤0.02% within this temperature range, and the cracking rate increases sharply when the temperature is higher than 48°C;

[0124] The reflux ratio is controlled at 5:1, and the purity is ≤99.95% when the reflux ratio is lower than 4:1, and the production efficiency decreases by ≥25% when the reflux ratio is higher than 6:1;

[0125] (3) The remaining steps: same as Example 5;

[0126] Product performance: electronic grade n-hexane product 8 is obtained, with a purity of 99.98%, a thermal cracking impurity of 0.015%, a metal ion of 3 ppb, an aromatic hydrocarbon of 80 ppm, and a moisture content of 6 ppm.

[0127] Example 9

[0128] (1) On the basis of Example 5, adjust the atmospheric distillation + vacuum distillation step, and the remaining steps are completely consistent with Example 5:

[0129] (2) Atmospheric distillation post-processing:

[0130] The crude n-hexane obtained in Example 5 is transferred into a 45-plate vacuum distillation column, which is a plate column, and the number of plates needs to meet the requirement that the residual heavy components are ≤0.05%, and the plate column can be replaced by a packed column;

[0131] The vacuum degree is controlled at 0.098 MPa, and the energy consumption increases by ≥40% when the vacuum degree is lower than 0.092 MPa, and the boiling point rises to cause cracking rate ≥0.03% when the vacuum degree is higher than 0.098 MPa;

[0132] The overhead temperature is controlled at 48°C, and the thermal cracking rate of n-hexane is ≤0.02% within this temperature range, and the cracking rate increases sharply when the temperature is higher than 48°C;

[0133] Reflux ratio control is 6:1, purity ≤99.95% when reflux ratio is lower than 4:1, production efficiency decrease ≥25% when reflux ratio is higher than 6:1;

[0134] (3) The remaining steps: same as example 5;

[0135] Product performance: electronic grade n-hexane product 9 is obtained, with purity 99.99%, thermal cracking impurities 0.01%, metal ions 3 ppb, aromatic hydrocarbons 80 ppm, and moisture 6 ppm.

[0136] Example 10:

[0137] (1) Based on example 8, add the step of ultraviolet oxidation-adsorption combination, and the remaining steps are completely consistent with example 8:

[0138] (2) Ultraviolet oxidation treatment:

[0139] After vacuum rectification, the fraction is introduced into the ultraviolet reactor with a wavelength of 240 nm. This wavelength range can generate enhanced oxidation by ozone, avoiding the degradation of n-hexane caused by wavelengths of 180-220 nm.

[0140] The power of the ultraviolet reactor is 80 W. When the power is lower than 80 W, the oxidation efficiency is ≤60%, and when the power is higher than 120 W, there is no obvious efficiency improvement.

[0141] The volume ratio of oxygen introduced is 0.3%. This amount needs to meet the oxidation rate of unsaturated hydrocarbons ≥85%. Excessive oxygen will generate peroxides, and insufficient oxidation will not be complete.

[0142] The reaction temperature is controlled at 32℃. When the temperature is lower than 32℃, the reaction time is ≥40min, and when the temperature is higher than 38℃, the risk of peroxide generation increases.

[0143] The reaction time is 25min, which needs to oxidize unsaturated hydrocarbons into polar oxides such as epoxy alkane and alcohol.

[0144] Adsorption connection:

[0145] After oxidation, the material is directly introduced into the composite adsorption column of example 5, without additional equipment. The existing adsorbent is used to adsorb oxides, which needs to meet the requirement of unsaturated hydrocarbons ≤8ppm.

[0146] (3) The remaining steps: same as example 8;

[0147] Product performance: electronic grade n-hexane product 10 is obtained, with unsaturated hydrocarbons 6ppm, no isomer impurities, purity 99.98%, thermal cracking impurities 0.015%, metal ions 3 ppb, aromatic hydrocarbons 80 ppm, and moisture 6 ppm.

[0148] Example 11:

[0149] (1) Based on Example 8, an ultraviolet synergistic hydrogen peroxide oxidation-adsorption combined step is added, and the remaining steps are completely consistent with Example 8:

[0150] (2) Ultraviolet synergistic hydrogen peroxide oxidation treatment:

[0151] After vacuum rectification, the fraction is passed into a ultraviolet reactor with a wavelength of 250 nm. This wavelength range can generate ozone-enhanced oxidation, avoiding the degradation of n-hexane caused by wavelengths of 180-220 nm;

[0152] The power of the ultraviolet reactor is 100 W. When the power is less than 80 W, the oxidation efficiency is ≤60%, and when the power is higher than 120 W, there is no obvious efficiency improvement;

[0153] Add hydrogen peroxide with a mass ratio of 0.2% hydrogen peroxide. This concentration needs to meet the requirement that the oxidation rate of unsaturated hydrocarbons is ≥85%. Excessive hydrogen peroxide will generate peroxide, and insufficient hydrogen peroxide will result in incomplete oxidation;

[0154] The reaction temperature is controlled at 35°C. When the temperature is lower than 32°C, the reaction time is ≥40 min, and when the temperature is higher than 38°C, the risk of peroxide generation increases;

[0155] The reaction time is 30 min, and the unsaturated hydrocarbons need to be oxidized to polar oxides such as epoxy alkane and alcohol;

[0156] Adsorption connection:

[0157] After oxidation, the material is directly introduced into the composite adsorption column of Example 5 without additional equipment. The existing adsorbent is used to adsorb the oxides, and the unsaturated hydrocarbons need to be ≤8 ppm;

[0158] (3) The remaining steps: same as Example 8;

[0159] Product performance: electronic grade n-hexane product 11 is obtained, with unsaturated hydrocarbons of 4 ppm, no isomer impurities, purity of 99.98%, thermal cracking impurities of 0.015%, metal ions of 3 ppb, aromatic hydrocarbons of 80 ppm, and moisture of 6 ppm.

[0160] Example 12:

[0161] (1) Based on Example 8, an ultraviolet synergistic hydrogen peroxide oxidation-adsorption combined step is added, and the remaining steps are completely consistent with Example 8:

[0162] (2) Plasma oxidation treatment:

[0163] After vacuum rectification, the fraction is passed into a low-temperature plasma oxidation device. The power of this device is 50 W, and it needs to meet the requirements of no degradation of n-hexane and unsaturated hydrocarbons ≤8 ppm;

[0164] The volume ratio of oxygen is 0.7%, which needs to meet the requirement that the oxidation rate of unsaturated hydrocarbon is greater than or equal to 85%. If the amount of oxygen is excessive, peroxide will be generated, and if the amount of oxygen is insufficient, the oxidation will not be complete.

[0165] The reaction temperature is controlled at 38℃. If the temperature is lower than 32℃, the reaction time is greater than or equal to 40min, and if the temperature is higher than 38℃, the risk of generating peroxide increases.

[0166] The reaction time is 35min, and the unsaturated hydrocarbon needs to be oxidized to a polar oxide such as an epoxy alkane or an alcohol.

[0167] Adsorption connection:

[0168] After oxidation, the material directly enters the composite adsorption column of Example 5 without additional equipment, and the existing adsorbent is used to adsorb the oxide, which needs to meet the requirement that the unsaturated hydrocarbon is less than or equal to 8ppm.

[0169] (3) The remaining steps are the same as in Example 8.

[0170] Product performance: electronic grade n-hexane product 12 is obtained, which has 3ppm of unsaturated hydrocarbon, no isomer impurities, a purity of 99.98%, a thermal cracking impurity of 0.015%, a metal ion of 3ppb, an aromatic hydrocarbon of 80ppm, and a moisture content of 6ppm.

[0171] Comparative Example 1:

[0172] Only the raw material pretreatment, atmospheric distillation and ultra-clean filtration steps of Example 2 are retained. The raw material pretreatment uses a 5% volume of sodium hydroxide solution, and the mass fraction of the solution is 15%, which is beyond the parameter range of the present application. The reflux ratio of atmospheric distillation is 1:1, which is beyond the parameter range of the present application. Comparative sample 1 is obtained. Its performance is a metal ion of 30ppb, an aromatic hydrocarbon of 850ppm, a purity of 99.10%, a moisture content of 40ppm, an unsaturated hydrocarbon of 25ppm, and a particle size of 15 / mL.

[0173] Comparative Example 2:

[0174] In the composite adsorption step of Example 2, only ordinary activated alumina is used without modification or chelating resin, and the adsorbent ratio is 1:1. The remaining steps are consistent with Example 2. Comparative sample 2 is obtained. Its performance is a metal ion of 10ppb, an aromatic hydrocarbon of 250ppm, a purity of 99.70%, a moisture content of 15ppm, an unsaturated hydrocarbon of 25ppm, and a particle size of 8 / mL.

[0175] Comparative Example 3:

[0176] In Example 8, the conventional parameters of vacuum rectification were used: vacuum degree 0.085 MPa, overhead temperature 52°C, reflux ratio 2:1, all being conventional values in the prior art, and the remaining steps were consistent with Example 8 to obtain Comparative Sample 3. Its performance was purity 99.8%, thermal cracking impurities 0.05%, metal ions 3 ppb, aromatic hydrocarbons 80 ppm, moisture 6 ppm, and unsaturated hydrocarbons 15 ppm.

[0177] Comparative Example 4:

[0178] On the basis of Example 8, the UV oxidation-adsorption was replaced by Pd / C catalytic hydrogenation: Pd / C catalyst was used, hydrogen pressure was 0.2 MPa, and the reaction temperature was 45°C, and the remaining steps were consistent with Example 8 to obtain Comparative Sample 4. Its performance was unsaturated hydrocarbons 12 ppm, containing 0.03% hexane isomers, purity 99.97%, thermal cracking impurities 0.015%, metal ions 2 ppb, aromatic hydrocarbons 55 ppm, and moisture 4 ppm.

[0179] Table 1. Results of basic performance tests of Examples 1-6, Comparative Examples 1-2, and commercially available samples

[0180]

[0181] Table 2. Results of basic performance tests of Examples 7-12 and Comparative Examples 3-4

[0182]

[0183] The test results are explained as follows:

[0184] (1) As the amount of raw material increased from 50 L to 200 L, by adjusting the amount of sodium hydroxide, the number of water washes, the height of the adsorption column, and other parameters, the purity of n-hexane increased from 99.85% to 99.92%, the metal ions decreased from 10 ppb to 6 ppb, and the particle size decreased from 6 / mL to 4 / mL, proving the adaptability of the basic process of the present application to different amounts of raw materials, and by synchronously adjusting the parameters, the impurity removal efficiency can be stably controlled, avoiding performance fluctuations caused by an increase in the amount of raw material.

[0185] (2) Compared with the basic scheme of Example 2, Examples 4-6 used a combination of molecular sieves + modified adsorbent + chelating resin (ratio 1:1:1 to 3:3:1), which reduced the metal ions from 8 ppb to 2 ppb and the aromatic hydrocarbons from 180 ppm to 70 ppm, and the moisture was stably ≤8 ppm.

[0186] The key reason is that the amino / hydroxyl groups of the modified adsorbent form π-π interactions with aromatic hydrocarbons, and the amino phosphonic acid / carboxylic acid groups of the chelating resin form stable chelates with metal ions, achieving the simultaneous removal of water, aromatic hydrocarbons, and metal ions, and solving the limitations of single adsorbent impurity removal in the basic scheme.

[0187] (3) Based on the adsorption optimization in Example 5, Examples 7-9 adjust the parameters of vacuum rectification, and the purity of n-hexane is increased from 99.95% to 99.99%, and the pyrolysis impurities are reduced from 0.03% to 0.01%.

[0188] The core advantage is that the balance of low boiling point and low cracking in the medium-high vacuum range, the high reflux ratio (5:1-6:1) strengthens the separation of heavy components, and avoids the high energy consumption or cracking risk caused by high temperature caused by conventional low vacuum.

[0189] (4) On the basis of rectification optimization, Examples 10-12 use ultraviolet / plasma oxidation combined with adsorption, and the unsaturated hydrocarbon is reduced from 15ppm to 3ppm, and no hexane isomer is generated.

[0190] The technical logic is that 240-250nm ultraviolet light or low-temperature plasma oxidizes olefins into polar epoxy alkane / alcohol, and the composite adsorption column can simultaneously adsorb the oxidation products without additional equipment, which not only avoids the noble metal cost and isomerization defects of hydrogenation method, but also realizes the deep removal of unsaturated hydrocarbons, which is crucial for semiconductor high-temperature processes (such as 200℃ annealing), which can avoid the increase of leakage current caused by the polymerization of unsaturated hydrocarbons.

[0191] (5) The difference between the comparative example and the present application:

[0192] Comparative example: metal ions 30ppb, aromatic hydrocarbon 850ppm, much higher than Examples 1-12, proving that composite adsorption is the key step for impurity control;

[0193] Comparative example 2: metal ions 10ppb, aromatic hydrocarbon 250ppm, which is 3-3.1 times of Example 5, highlighting the necessity of modified adsorbent combination;

[0194] Comparative example 3: purity 99.80%, pyrolysis impurities 0.05%, performance only reaches the basic level of Example 7, verifying the creativity of rectification parameter optimization;

[0195] Comparative example 4: unsaturated hydrocarbon 12ppm, containing 0.03% isomer, Example 11 unsaturated hydrocarbon only 4ppm and no isomer, showing the advantage of oxidation combined scheme.

[0196] (6) The core indicators of the present application examples are better than the commercially available samples: metal ions less than 3ppb (commercially available 32ppb), moisture less than 6ppm (commercially available 40ppm), aromatic hydrocarbon less than 80ppm (commercially available 920ppm), leakage current less than 2×10 -9 A (commercially available 5×10 -8 A), proving that the technical scheme of the present application can meet the cleaning requirements of 12-inch advanced process (such as 7nm node), while the commercially available samples are only suitable for 28nm and above nodes.

[0197] To verify the practicability, adaptability and technical advantages of the electronic-grade n-hexane prepared by each embodiment of the present application in the semiconductor cleaning scene, compare with the prior art, and determine the ability to meet the cleaning needs of advanced semiconductor processes, and ensure that the test process is repeatable and the results are verifiable.

[0198] (1) Test sample group

[0199] Basic process group: Example 1, Example 2, Example 3.

[0200] Adsorption optimization group: Example 4, Example 5, Example 6.

[0201] Rectification-adsorption combined optimization group: Example 7, Example 8, Example 9.

[0202] Oxidation-adsorption combined optimization group: Example 10, Example 11, Example 12.

[0203] (2) Control sample group

[0204] Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4.

[0205] Commercially available electronic-grade n-hexane sample.

[0206] Test items and methods:

[0207] (1) Semiconductor wafer cleaning effect test

[0208] Test object: 12-inch silicon wafer, preset surface contaminants: particles >0.5 μm, organic residues, metal ions.

[0209] Cleaning process: using immersion + ultrasonic cleaning mode, cleaning temperature 25℃, ultrasonic power 300W, cleaning time 5min, then rinsing with ultrapure water 3 times, and blowing dry with nitrogen.

[0210] Detection method:

[0211] Particle residue: Scanning Electron Microscope (SEM) counts the number of particles >0.5 μm on the wafer surface.

[0212] Organic contaminant residue: X-ray photoelectron spectroscopy (XPS) analyzes the residual amount of C element on the wafer surface.

[0213] Metal ion residue: Inductively coupled plasma mass spectrometry (ICP-MS) detects the total amount of Na, K, Fe, Cu on the wafer surface.

[0214] Semiconductor device performance impact test as follows:

[0215] Test object: 7nm node MOSFET device (unwashed test sample, sample after cleaning of each sample).

[0216] Detection method:

[0217] Leakage current: semiconductor parameter analyzer tests the gate leakage current of the device, test voltage 1.2V, temperature 25℃.

[0218] Yield: statistics of the proportion of 1000 devices working normally after cleaning (leakage current <2x10 -9 A is the qualified standard).

[0219] High temperature stability: after cleaning, the device is placed in a 200℃ annealing furnace for 2h, and the change rate of leakage current is retested after cooling.

[0220] Process adaptability test as follows:

[0221] Raw material amount adaptability: the cleaning effect consistency of comparative example 1, example 2 and example 3, with the variation coefficient of particle residue and metal ion residue <5% as the adaptability standard.

[0222] Process node adaptability: use example 12 and commercially available samples to clean 28nm, 14nm and 7nm node devices, respectively, and detect whether the leakage current meets the requirements of each node (28nm≤5x10 -8 A, 14nm≤1x10 -8 A, 7nm≤2x10 -9 A).

[0223] Long-term stability test as follows:

[0224] Sample storage conditions: the sample of example 12 is sealed and stored in an environment of 40℃ and relative humidity of 50% for 6 months.

[0225] Detection content: test purity, moisture, aromatic hydrocarbon and metal ion content every month, and test cleaning effect (particle residue, leakage current) at the same time, and observe the change rate of the index.

[0226] Test results as follows:

[0227] Table 3 wafer cleaning effect results

[0228]

[0229] Table 4 device performance impact results

[0230]

[0231] Process adaptability results as follows:

[0232] Raw material quantity suitability: The coefficient of variation for particle residue in Examples 1, 2, and 3 was 3.2%, and the coefficient of variation for metal ion residue was 2.8%, both <5%, which meets the production requirements for different raw material quantities.

[0233] Process node adaptability:

[0234] Example 12: The leakage current of 28nm, 14nm, and 7nm devices all met the standard (1×10⁻⁶ respectively). -8 A, 5×10 -9 A, 8×10 -10 A).

[0235] Commercially available samples: Leakage current meets standards for cleaning 28nm devices (4×10) -8 A) The leakage current of 14nm and 7nm devices exceeded the standard during cleaning (1.5×10⁻⁶ respectively). -7 A, 3×10 -7 A).

[0236] The long-term stability results are as follows:

[0237] Example 12: Sample stored for 6 months:

[0238] The purity decreased from 99.98% to 99.97%, the moisture content increased from 6 ppm to 8 ppm, the aromatic hydrocarbon content increased from 80 ppm to 85 ppm, and the metal ion content increased from 3 ppb to 4 ppb.

[0239] After cleaning, 3 wafer particles remained per wafer, and the device leakage current was 1×10⁻⁶. -9 A, all meet the 7nm process requirements.

[0240] The test results are as follows:

[0241] Practicality verification: The electronic-grade n-hexane prepared in each embodiment of the present invention can effectively clean semiconductor wafers, and the leakage current and yield of the cleaned devices meet the requirements of semiconductor process. Among them, Examples 7-12 can be stably adapted to 12-inch 7nm advanced process, proving that the invention has practical application value.

[0242] Comparative Examples 1-2: Examples 4-6 used a combination of molecular sieve, modified adsorbent, and chelating resin for adsorption, which reduced the residual metal ions from 30 ppb to 3 ppb and aromatic hydrocarbons from 850 ppm to 80 ppm, overcoming the limitations of single adsorbents in impurity removal and demonstrating technological improvement.

[0243] Comparative Example 3: Examples 7-9 By optimizing the reduced pressure distillation parameters, the purity increased from 99.80% to 99.99%, and the thermal cracking impurities decreased from 0.05% to 0.01%, avoiding the problems of high energy consumption and high cracking risk of conventional distillation.

[0244] Comparative Example 4, commercial sample: Examples 10-12 by UV / plasma oxidation, unsaturated hydrocarbons from 25 ppm to 3 ppm, and no isomer generation, after cleaning device leakage current is lower than a commercial sample of an order of magnitude, 7 nm process, significantly better than the prior art, embodying the inventive.

[0245] Adaptability and stability: the process of the application can adapt to 50-200L different raw material quantity, and the sample still meets the advanced process cleaning demand after 6 months of storage, which proves that the technical scheme is stable and reliable, and has industrialization application potential.

[0246] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and do not limit the application to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of the specification. The specification selects and describes these embodiments in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and utilize the application.

Claims

1. A process for the production of electronic grade n-hexane for semiconductor cleaning, characterized in that, It comprises the following steps: (1) raw material pretreatment: taking industrial-grade n-hexane, adding sodium hydroxide solution with a volume fraction of 8%-12% and a dosage of 3%-8% of the volume of the raw material to neutralize, taking the oil phase after standing and separating; washing with deionized water with a resistivity of ≥15 MΩ·cm 2-4 times, the amount of water used is 8%-15% of the volume of the raw material, and the pH of the water phase after neutralization is controlled to be 6.8-7.2; adding 0.3%-0.8% of the mass of the raw material of anhydrous magnesium sulfate or anhydrous sodium sulfate to dry, filtering after standing, and obtaining pretreated n-hexane with water content ≤60 ppm; (2) atmospheric distillation: the pretreated n-hexane is sent to a packed distillation column or a plate distillation column with 25-35 trays, the overhead temperature is controlled at 66-70℃, and the reflux ratio is 2:1-4:1, and the overhead fraction is collected to obtain crude n-hexane; (3) Composite adsorption: passing crude n-hexane through an adsorption column with a height of 40-60 cm at a flow rate of 0.8-1.2 mL / min; the adsorption column is filled with molecular sieve and activated alumina at a mass ratio of 1:1-1:2, wherein the molecular sieve is 3A, 4A or 5A, and the specific surface area of the activated alumina is ≥280 m 2 / g; the adsorption temperature is controlled at 35-45°C to obtain adsorbed n-hexane; (4) Distillation: distilling the adsorbed n-hexane under reduced pressure to obtain refined n-hexane. (5) Purification: purifying the refined n-hexane by passing it through a column filled with activated alumina at a flow rate of 0.8-1.2 mL / min to obtain purified n-hexane. (6) Degassing: degassing the purified n-hexane at a flow rate of 0.8-1.2 mL / min to obtain degassed n-hexane. (7) Filtration: filtering the degassed n-hex (4) ultra-clean filtration: the adsorbed n-hexane is filtered through a filter core to obtain electronic-grade n-hexane; the filter core material is polytetrafluoroethylene or polypropylene.

2. The production method according to claim 1, characterized by, In step (3), the adsorbent also includes metal chelate resin, the mass ratio of molecular sieve, activated alumina and metal chelate resin is 1:1:1-3:3:1; the metal chelate resin is amino phosphonic acid type, carboxylic acid type or imine diacetic acid type; the adsorption temperature is adjusted to 45-55℃, and the flow rate is adjusted to 0.6-1.0 mL / min.

3. The preparation method according to claim 1, characterized in that, After step (2) atmospheric distillation, it also includes a vacuum distillation step: crude n-hexane is sent to a vacuum distillation column, the vacuum degree, overhead temperature and reflux ratio are controlled, and the overhead fraction is collected; the vacuum distillation column is a plate column or a packed column with 35-45 trays; the vacuum degree is 0.092-0.098 MPa, the overhead temperature is 42-48℃, and the reflux ratio is 4:1-6:

1.

4. The production method according to claim 3, characterized by, After vacuum distillation, it also includes an oxidation-adsorption combined treatment step: the vacuum distillation fraction is subjected to ultraviolet oxidation treatment, and the oxidized material is directly introduced into the composite adsorption column of step (3); the wavelength of ultraviolet oxidation is 240-250 nm, the power is 80-120 W, the oxygen volume ratio is 0.3%-0.7%, the reaction temperature is 32-38℃, and the reaction time is 25-35 min.

5. The preparation method according to claim 4, characterized in that, The ultraviolet oxidation is replaced by ultraviolet synergistic hydrogen peroxide oxidation; the mass ratio of hydrogen peroxide to material is 0.2%-0.5%.

6. The preparation method according to claim 5, characterized in that, The ultraviolet oxidation is replaced by plasma oxidation; the power of the plasma oxidation equipment is 50-80 W, the oxygen volume ratio is 0.3%-0.7%, the reaction temperature is 32-38℃, and the reaction time is 30-35 min.

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