Purification method of ultra-clean high-purity G5-grade PGMEA solution

Abstract

The invention discloses a purification method of an ultra-clean high-purity G5-grade PGMEA solution, which comprises the following steps: pretreatment: pretreating an industrial-grade PGMEA raw material to obtain a pretreated material, and carrying out preliminary filtration and impurity removal on the industrial-grade PGMEA raw material during pretreatment; light component removal rectification: the pretreated material enters a light component removal rectification tower, light components are separated out from the tower top, and the tower bottom is primarily purified PGMEA; resin purification: enabling the primarily purified PGMEA to sequentially pass through chelate resin, cation exchange resin and anion exchange resin to remove metal ions and other trace impurities in the primarily purified PGMEA so as to obtain resin purified PGMEA; the resin purified PGMEA enters a de-heavy rectifying tower, heavy components are separated out from the tower bottom, and de-heavy purified PGMEA is obtained from the tower top; and performing ultrafiltration circulation. By combining multi-stage rectification, resin purification and ultrafiltration technologies, light components, metal ions, organic impurities and submicron particles in the industrial-grade PGMEA raw material are effectively removed, so that the product reaches the ultra-clean high-purity G5-grade standard.

Description

Technical Field

[0001] The present invention relates to the field of purification of ultrapure and high-purity reagents, and particularly to a method for purifying ultrapure and high-purity G5-level PGMEA solution. Background Art

[0002] In the highly precise and complex field of semiconductor manufacturing, the lithography process, as one of the core links in chip manufacturing, is of great importance. And PGMEA, as the main solvent of photoresist, plays an indispensable role in the lithography process. In the preparation stage of photoresist, PGMEA can fully dissolve various photoresist components, ensuring that the photoresist has good uniformity and stability, laying a foundation for subsequent uniform coating on the silicon wafer. When the photoresist is coated on the surface of the silicon wafer, the volatile characteristics of PGMEA can help the photoresist dry quickly, forming a uniform and appropriately thick photoresist film. In the developing process after lithography, PGMEA can also assist in removing the unexposed photoresist, enabling the pattern of the exposed part to be accurately revealed.

[0003] As semiconductor technology continues to advance towards 7nm and below processes, the integration density of chips has increased significantly, and the feature size has been continuously reduced. This places extremely high requirements on the accuracy of the lithography process, and the accuracy of the lithography process highly depends on the quality of photoresist and related solvents. The ultrapure and high-purity G5-level PGMEA solution not only needs to meet extremely strict impurity content limits, such as the metal ion content needs to be lower than 0.01 ppb, and the content of particulate impurities (≥0.1μm) needs to be controlled at an extremely low level, but also must achieve continuous and efficient production during the production process. Because in large-scale semiconductor manufacturing production lines, only continuous, stable and efficient supply of PGMEA can ensure high efficiency and high yield in chip manufacturing, thereby meeting the increasingly high standards of the semiconductor industry.

[0004] Traditional PGMEA refining methods are mostly based on single processes, such as multi-stage distillation and simple filtration, etc. These methods have serious defects in removing impurities. Multi-stage distillation mainly relies on the difference in the boiling points of substances for separation. However, for impurities with boiling points close to that of PGMEA, multi-stage distillation is difficult to achieve effective separation. The boiling points of many organic impurities are relatively close to that of PGMEA, and they are easily distilled out together with PGMEA during distillation, resulting in incomplete removal. For metal ions and submicron-sized particulate impurities, multi-stage distillation is even more powerless. The simple filtration method can remove some larger particulate impurities, but its removal effect on metal ions, organic impurities, and submicron-sized particulate impurities is minimal. Metal ions exist in the solution in ionic form and cannot be removed by ordinary filtration methods; while submicron-sized particulate impurities are extremely small in size, and the pore sizes of conventional filter media cannot effectively intercept them.

[0005] Some traditional PGMEA refining technologies rely on long-term operation under high temperature and high pressure conditions to achieve purification. Under high temperature and high pressure environment, not only a large amount of energy is consumed to maintain the reaction conditions, but also the requirements for equipment are extremely harsh. The purchase cost of high temperature and high pressure equipment is high, and its materials need to have multiple properties such as high temperature resistance, high pressure resistance and corrosion resistance. At the same time, the sealing requirements of the equipment are also extremely high. In addition, long-term operation under high temperature and high pressure makes the equipment more prone to wear and corrosion, requiring more frequent maintenance and replacement of parts, which further increases the maintenance cost of the equipment. These factors combined have kept the production cost high, seriously affecting the economic benefits and market competitiveness of the company.

[0006] Some traditional PGMEA purification processes use chemical reagents in the process. Although these chemical reagents can help remove impurities to a certain extent, they bring the risk of introducing secondary pollution. Chemical reagents themselves may contain impurities, which will remain in the PGMEA solution during use and become new impurities. Chemical reagents may also react chemically with PGMEA or other impurities to generate by-products that are difficult to separate, thereby affecting the purity of the product. When using chemical reagents containing metal ions for impurity removal, even a small amount of metal ions remaining will cause the metal ion content in PGMEA to exceed the standard and fail to meet the ultra-clean high-purity G5 level requirements.

[0007] After in-depth research on the physicochemical properties of PGMEA, including its boiling point, solubility, chemical stability, etc., the team of the present invention closely combined the actual needs of semiconductor processes for PGMEA, innovatively integrated multi-stage distillation, resin purification and ultrafiltration technology, and proposed a new purification process. Multi-stage distillation technology can utilize the difference in boiling points between PGMEA and impurities to effectively separate light components (such as alcohol impurities) and heavy components (such as polymers), and preliminarily remove most impurities. Resin purification technology uses cation exchange resins, chelating resins and anion exchange resins to specifically remove metal ions and other trace impurities, greatly improving the purity of the product. Ultrafiltration technology can accurately remove submicron particles through multi-stage filter element filtration to ensure that the cleanliness of the solution meets SEMI standards. This integrated process not only improves the quality of the finished product, enabling it to meet the strict requirements of ultra-clean and high-purity G5 level, but also simplifies the production process and reduces production costs by optimizing process steps and parameters, providing a reliable, efficient and economical PGMEA purification solution for high-end fields such as semiconductor manufacturing.

[0008] The boiling point of a substance is one of its important physical properties, and the boiling points of different substances often vary under the same pressure. The boiling points of PGMEA, alcohol impurities, polymers and other impurities are different. In the multi-stage distillation process, the industrial-grade PGMEA raw material is first heated to an appropriate temperature to cause partial vaporization. Since the boiling points of light components (such as alcohol impurities) are relatively low, they will vaporize first and rise to the top of the tower, and are condensed and collected through the condensation device at the top of the tower, so as to separate the light components from PGMEA. The heavy components (such as polymers) will remain at the bottom of the tower due to their high boiling points. By controlling parameters such as the temperature, pressure, and reflux ratio of the distillation column, the separation effect can be precisely adjusted to ensure the effective removal of light components and heavy components and improve the purity of PGMEA.

[0009] Cation exchange resins, chelating resins and anion exchange resins have different ion exchange and adsorption characteristics. Cation exchange resins can undergo exchange reactions with cations in the solution, adsorb metal cations (such as Na+, Fe3+, Cu2+ etc.) in the solution onto the resin, thereby removing cation impurities. Chelating resins have extremely strong chelating ability for specific metal ions and can selectively adsorb heavy metal ions to further reduce the metal ion content in the solution. Anion exchange resins remove anion impurities by undergoing exchange reactions with anions in the solution. By reasonably combining and using these three resins and controlling conditions such as the flow rate and temperature of the solution, metal ions and other trace impurities in the PGMEA solution can be effectively removed, enabling the product to meet higher purity standards.

[0010] Ultrafiltration is a membrane separation-based technology that filters a solution using a filter element with a specific pore size. The size of submicron particles is larger than the pore size of the ultrafiltration filter element. When the PGMEA solution passes through multi-stage ultrafiltration filter elements (such as 0.5μm, 0.2μm, 0.1μm pore size filter elements), the submicron particles will be intercepted by the filter element, while the PGMEA molecules can pass through the filter element smoothly, thus achieving the removal of particulate impurities. This step-by-step filtration method can ensure that particulate impurities in the solution are removed as much as possible, making the cleanliness of the solution meet the SEMI standard and meet the strict requirements for the cleanliness of PGMEA in high-end fields such as semiconductor manufacturing. Summary of the Invention

[0011] The purpose of the present invention is to provide a purification method for ultra-high purity G5 grade PGMEA solution.

[0012] The innovation of the present invention lies in the innovative combination of multi-stage distillation, resin purification and ultrafiltration technologies, realizing the efficient removal of light components, metal ions and submicron particles in the PGMEA solution. By optimizing the flow rate and temperature parameters of resin purification, the removal efficiency of metal ions is significantly improved, enabling the product purity to reach the G5 grade standard.

[0013] To achieve the above-mentioned invention objective, the technical solution of the present invention is as follows:

[0014] A purification method for ultra-high purity G5 level PGMEA solution, comprising the following steps:

[0015] (1) Pretreatment: Pretreat the industrial grade PGMEA raw material to obtain a pretreated material. During pretreatment, the industrial grade PGMEA raw material is preliminarily filtered and impurities are removed.

[0016] (2) Light component removal rectification: Feed the pretreated material into a light component removal rectification column. The light components are separated from the top of the column, and the bottom of the column is the preliminarily purified PGMEA.

[0017] (3) Resin purification: Pass the preliminarily purified PGMEA through a chelating resin, a cation exchange resin, and an anion exchange resin in sequence to remove metal ions and other trace impurities in the preliminarily purified PGMEA to obtain resin-purified PGMEA.

[0018] (4) Heavy component removal rectification: Feed the resin-purified PGMEA into a heavy component removal rectification column. The heavy components are separated from the bottom of the column, and the top of the column obtains the heavy component-removed and purified PGMEA.

[0019] (5) Ultrafiltration cycle: Feed the heavy component-removed and purified PGMEA into an ultrafiltration cycle system, and filter it through PTFE filter elements with pore sizes of 0.5μm, 0.2μm, and 0.1μm step by step to remove submicron particles to obtain the finished product.

[0020] Further, during the light component removal rectification process, the top temperature is 140 - 160°C, the bottom temperature is 150 - 170°C, the reflux ratio is 15, and the pressure is 0.1 - 0.2 MPa.

[0021] Further, the number of theoretical plates of the light component removal rectification column is 100 - 150, the material is 316L stainless steel and the inner wall is polished to below 0.4μm.

[0022] Further, the cation exchange resin is a strong acid type styrene-based cation resin with a pore size of 0.3 - 1 mm; the chelating resin is a macroporous polystyrene-based special adsorption resin with a pore size of 0.5 - 2 nm; the anion exchange resin is a strong base type styrene-based resin with a pore size of 0.5 - 2 nm.

[0023] Further, during the resin purification, control the flow rate so that the preliminarily purified PGMEA runs at a flow rate of 3 - 20 times the volume of the cation exchange resin, and control the temperature at 20 - 25°C.

[0024] Further, the flow rate in the ultrafiltration cycle is 0.3 - 0.5 m 3 / h, and the temperature is 20 - 30°C.

[0025] Further, buffer storage tanks are added after the light component removal rectification column and before resin purification, as well as after resin purification and before the heavy component removal rectification column.

[0026] Further, the number of theoretical plates of the light component removal rectification column is 150 - 200, the material is 316L stainless steel and the inner wall is polished to below 0.4 μm. When performing light component removal rectification, the temperature range is controlled at 150 - 180 °C, and the pressure is 0.05 - 0.1 MPa.

[0027] The beneficial effects of the present invention are as follows:

[0028] 1. In the present invention, through the combination of multi-stage rectification and resin purification, the purity of the PGMEA solution is significantly improved, meeting the requirements of ultra-high purity G5 level.

[0029] 2. The present invention optimizes the process parameters, reduces the production cost, and improves the production efficiency at the same time. Specific Embodiments

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0031] Example 1: A purification method for an ultra-high purity G5 level PGMEA solution, comprising the following steps:

[0032] (1) Pretreatment: The industrial grade PGMEA raw material is pretreated to obtain a pretreated material. During pretreatment, the industrial grade PGMEA raw material is preliminarily filtered and impurities are removed.

[0033] (2) Light component removal rectification: The pretreated material enters the light component removal rectification column, and the light components are separated from the top of the column, and the bottom of the column is the preliminarily purified PGMEA.

[0034] During the light component removal rectification process, the top temperature of the column is 140 °C, the bottom temperature of the column is 150 °C, the reflux ratio is 15, and the pressure is 0.1 MPa.

[0035] The number of theoretical plates of the light component removal rectification column is 100, the material is 316L stainless steel and the inner wall is polished to below 0.4 μm.

[0036] (3) Resin purification: The preliminarily purified PGMEA enters the buffer storage tank, and then sequentially passes through a chelating resin, a cation exchange resin, and an anion exchange resin to remove metal ions and other trace impurities in the preliminarily purified PGMEA to obtain resin-purified PGMEA;

[0037] The cation exchange resin is a strong acid type styrene-based cation resin with a pore size of 0.3 - 1 mm;

[0038] The chelating resin is a macroporous polystyrene-based special adsorption resin with a pore size of 0.5 - 2 nm; the anion exchange resin is a strong base type styrene-based resin with a pore size of 0.5 - 2 nm.

[0039] When purifying the resin, control the flow rate so that the preliminarily purified PGMEA runs at a flow rate three times the volume of the resin, and control the temperature at 20 °C.

[0040] (4) Heavy component removal rectification: Feed the resin-purified PGMEA into the buffer storage tank, and then into the heavy component removal rectification column. The heavy components are separated from the bottom of the column, and the heavy component-removed and purified PGMEA is obtained at the top of the column.

[0041] The theoretical number of plates of the heavy component removal rectification column is 150, and the material is 316L stainless steel with the inner wall polished to below 0.4 μm. When performing heavy component removal rectification, control the temperature range at 150 °C and the pressure at

[0042] 0.05 MPa.

[0043] (5) Ultrafiltration cycle: Feed the heavy component-removed and purified PGMEA into the ultrafiltration cycle system, and filter it successively through PTFE filter elements with pore sizes of 0.5 μm, 0.2 μm, and 0.1 μm to remove submicron particles to obtain the finished product.

[0044] The flow rate in the ultrafiltration cycle is 0.3 m 3 / h, and the temperature is 20 °C.

[0045] Test results: Metal ion content: 3 ppt; Organic impurity content: 1.5 ppm; Particle impurities: 5 pieces / mL.

[0046] Example 2: A method for purifying an ultra-high purity G5-level PGMEA solution, comprising the following steps:

[0047] (1) Pretreatment: Pretreat the industrial-grade PGMEA raw material to obtain the pretreated material. During pretreatment, perform preliminary filtration and impurity removal on the industrial-grade PGMEA raw material.

[0048] (2) Light component removal rectification: Feed the pretreated material into the light component removal rectification column. The light components are separated from the top of the column, and the preliminarily purified PGMEA is obtained at the bottom of the column.

[0049] During the light component removal rectification process, the top temperature of the column is 150 °C, the bottom temperature of the column is 160 °C, the reflux ratio is 15, and the pressure is 0.15 MPa.

[0050] The theoretical number of plates of the light component removal rectification column is 120, and the material is 316L stainless steel with the inner wall polished to below 0.4 μm.

[0051] (3) Resin purification: Feed the preliminarily purified PGMEA into the buffer storage tank, and then pass it successively through chelating resin, cation exchange resin, and anion exchange resin to remove metal ions and other trace impurities in the preliminarily purified PGMEA to obtain resin-purified PGMEA.

[0052] The cation exchange resin is a strong acid type styrene-based cation resin with a pore size of 0.3 - 1 mm;

[0053] The chelating resin is a macroporous polystyrene-based special adsorption resin with a pore size of 0.5 - 2 nm; the anion exchange resin is a strong base type styrene-based resin with a pore size of 0.5 - 2 nm.

[0054] When purifying the resin, control the flow rate so that the preliminarily purified PGMEA runs at a flow rate 10 times the resin volume, and control the temperature at 22 °C.

[0055] (4) Heavy component removal rectification: Feed the resin-purified PGMEA into the buffer storage tank, and then into the heavy component removal rectification tower. The heavy components are separated from the bottom of the tower, and the PGMEA purified by heavy component removal is obtained at the top of the tower;

[0056] The number of theoretical plates of the heavy component removal rectification tower is 175, the material is 316L stainless steel and the inner wall is polished to less than 0.4 μm. When performing heavy component removal rectification, control the temperature range at 165 °C and the pressure at

[0057] 0.08 MPa.

[0058] (5) Ultrafiltration cycle: Feed the PGMEA purified by heavy component removal into the ultrafiltration cycle system, and filter it step by step using PTFE filter elements with pore sizes of 0.5 μm, 0.2 μm, and 0.1 μm to remove submicron particles to obtain the finished product.

[0059] The flow rate in the ultrafiltration cycle is 0.4 3 / h, and the temperature is 25 °C.

[0060] Test results: Metal ion content: 4 ppt; Organic impurity content: 1.8 ppm; Particle impurities: 4 pieces / mL.

[0061] Example 3: A method for purifying an ultra-high purity G5 grade PGMEA solution, comprising the following steps:

[0062] (1) Pretreatment: Pretreat the industrial grade PGMEA raw material to obtain the pretreated material. During pretreatment, perform preliminary filtration and impurity removal on the industrial grade PGMEA raw material;

[0063] (2) Light component removal rectification: Feed the pretreated material into the light component removal rectification tower. The light components are separated from the top of the tower, and the preliminarily purified PGMEA is obtained at the bottom of the tower;

[0064] During the light component removal rectification process, the top temperature of the tower is 160 °C, the bottom temperature of the tower is 170 °C, the reflux ratio is 15, and the pressure is 0.2 MPa.

[0065] The number of theoretical plates of the light component removal rectification tower is 150, the material is 316L stainless steel and the inner wall is polished to less than 0.4 μm.

[0066] (3) Resin purification: The preliminarily purified PGMEA is fed into a buffer storage tank and then sequentially passes through chelating resin, cation exchange resin, and anion exchange resin to remove metal ions and other trace impurities in the preliminarily purified PGMEA, obtaining resin-purified PGMEA;

[0067] The cation exchange resin is a strong acid styrene-based cation resin with a pore size of 0.3 - 1 mm;

[0068] The chelating resin is a macroporous polystyrene-based special adsorption resin with a pore size of 0.5 - 2 nm; the anion exchange resin is a strong base styrene-based resin with a pore size of 0.5 - 2 nm.

[0069] During resin purification, the flow rate is controlled so that the preliminarily purified PGMEA runs at a flow rate 20 times the resin volume, and the temperature is controlled at 25°C.

[0070] (4) Heavy component removal distillation: The resin-purified PGMEA is fed into a buffer storage tank and then into a heavy component removal distillation column. The heavy components are separated from the bottom of the column, and the heavy component-removed and purified PGMEA is obtained at the top of the column;

[0071] The heavy component removal distillation column has 200 theoretical plates, is made of 316L stainless steel with an inner wall polished to below 0.4 μm. During heavy component removal distillation, the temperature range is controlled at 180°C and the pressure is

[0072] 0.1 MPa.

[0073] (5) Ultrafiltration cycle: The heavy component-removed and purified PGMEA is fed into an ultrafiltration cycle system and filtered through PTFE filter elements with pore sizes of 0.5 μm, 0.2 μm, and 0.1 μm step by step to remove submicron particles to obtain the finished product.

[0074] The flow rate in the ultrafiltration cycle is 0.5 m 3 / h, and the temperature is 30°C.

[0075] Test results: Metal ion content: 4.5 ppt; Organic impurity content: 1.5 ppm; Particle impurity: 5 pieces / mL.

[0076] The described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention.

Claims

1. A purification method for ultra-clean and high-purity G5-level PGMEA solution, characterized in that, It includes the following steps: (1) Pretreatment: Pretreat the industrial-grade PGMEA raw material to obtain a pretreated material. During pretreatment, the industrial-grade PGMEA raw material is preliminarily filtered and purified to remove impurities; (2) Light component removal by distillation: Feed the pretreated material into a light component removal distillation column. The light components are separated from the top of the column, and the bottom of the column is the preliminarily purified PGMEA; (3) Resin purification: Pass the preliminarily purified PGMEA successively through a chelating resin, a cation exchange resin, and an anion exchange resin to remove metal ions and other trace impurities in the preliminarily purified PGMEA to obtain resin-purified PGMEA; (4) Heavy component removal by distillation: Feed the resin-purified PGMEA into a heavy component removal distillation column. The heavy components are separated from the bottom of the column, and the top of the column obtains the heavy component-removed and purified PGMEA; (5) Ultrafiltration cycle: Feed the heavy component-removed and purified PGMEA into an ultrafiltration cycle system, and filter it successively using PTFE filter elements with pore sizes of 0.5 μm, 0.2 μm, and 0.1 μm to remove submicron particles to obtain the finished product.

2. The purification method of the ultra-high purity G5 level PGMEA solution according to claim 1, wherein During the light component removal by distillation process, the top temperature is 140-160 °C, the bottom temperature is 150-170 °C, the reflux ratio is 15, and the pressure is 0.1-0.2 MPa.

3. The purification method of the ultra-high purity G5 level PGMEA solution according to claim 1, wherein, The theoretical number of plates of the light component removal distillation column is 100-150, the material is 316L stainless steel, and the inner wall is polished to below 0.4 μm.

4. The purification method of the ultra-high purity G5 level PGMEA solution according to claim 1, characterized in that, The cation exchange resin is a strong acid type styrene-based cation resin with a pore size of 0.3-1 mm; the chelating resin is a macroporous polystyrene-based special adsorption resin with a pore size of 0.5-2 nm; The anion exchange resin is a strong base type styrene-based resin with a pore size of 0.5-2 nm.

5. The purification method of the ultra-high purity G5 level PGMEA solution according to claim 1, characterized in that, During resin purification, control the flow rate so that the preliminarily purified PGMEA runs at a flow rate 3-20 times the volume of the cation exchange resin, and control the temperature at 20-25 °C.

6. The purification method of the ultra-high purity G5 level PGMEA solution according to claim 1, characterized in that, The flow rate in the ultrafiltration cycle is 0.3 to 0.5 m 3 / h, and the temperature is 20 to 30 °C.

7. The purification method of the ultra-high purity G5 level PGMEA solution according to claim 1, characterized in that, Add buffer storage tanks after the light component removal distillation column and before resin purification, and after resin purification and before the heavy component removal distillation column.

8. The purification method of the ultra-high purity G5 level PGMEA solution according to claim 1, characterized in that, The theoretical number of plates of the light component removal distillation column is 150-200, the material is 316L stainless steel, and the inner wall is polished to below 0.4 μm. During light component removal by distillation, control the temperature range at 150-180 °C, and the pressure is 0.05-0.1 MPa.