An ebr solvent and its rectification preparation process

Abstract

The application discloses an EBR solvent and a rectification preparation process thereof, and belongs to the technical field of semiconductor material processing; wherein the EBR solvent comprises the following components in percentage: 95-98% of propylene glycol methyl ether acetate and 2-5% of propylene glyyl methyl ether. The EBR solvent is prepared by rectification recovery of waste liquid generated in a dilution cleaning process, and the main steps are as follows: S1, sedimentation filtration: filtering solid impurities in the waste liquid; S2, preliminary water removal: removing part of water in the filtered waste liquid through a common distillation tank to obtain primary waste liquid raw material; S3, feeding: introducing the primary waste liquid raw material into a rectification tower for intermittent distillation purification; S4, water removal: removing water in the primary waste liquid raw material by using an extractant; S5, extractant reflux; S6, extractant extraction: after the water is removed, the extractant is extracted; and S7, EBR solvent extraction. The application solves the problem that the purity of the effective component EBR solvent in the photoresist cleaning waste liquid is not high, and the recycling effect is poor.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor material processing technology, specifically relating to an EBR solvent and its distillation preparation process. Background Technology

[0002] During the photoresist coating and spin coating processes in semiconductor photolithography, the photoresist thickness at the wafer edges is typically several times the normal film thickness due to centrifugal force. This accumulation at the edges forms bulges, which can easily contaminate the photoresist exposure equipment and the bottom surface of the wafer. Therefore, a thinner is needed to clean the photoresist at the wafer edges and on the back side to prevent environmental and equipment contamination in subsequent processes. This process of removing the photoresist bulges at the wafer edges is called EBR (Edge Bead Removal), also known as photoresist edge line removal. The solvent used to dilute and clean the photoresist is also called the EBR solvent. The composition and ratio of the EBR solvent affect the degree of photoresist cleaning.

[0003] The EBR solvent, after being diluted and cleaned, is called dilution waste liquid. The composition of the EBR solvent in the dilution waste liquid remains unchanged. After further purification of the components of the EBR solvent in the dilution waste liquid, it can be reused. However, the purity of the purified EBR solvent affects the cleaning effect on photoresist when reused and whether it will affect the wafer itself. Ordinary distillation purification technology has a low recovery rate, and its recovery purity makes it unsatisfactory for cleaning photoresist when reused. Summary of the Invention

[0004] This invention provides an EBR solvent and its distillation preparation process. The EBR solvent is prepared from a mixed solvent obtained by mixing propylene glycol methyl ether acetate (PGMEA) and propylene glycol methyl ether (PGME) in a specific ratio. The diluted waste liquid is purified by batch distillation. Before batch distillation, a portion of the water in the waste diluted liquid is removed by distillation in a distillation tank, shortening the subsequent batch distillation time. Furthermore, the purity of the recovered EBR solvent is improved by setting and controlling parameters such as temperature and reflux ratio. This invention solves the problem of low purity in the current recovery of EBR solvent, the effective component in photoresist cleaning waste liquid, leading to poor recycling and reuse effects.

[0005] To achieve the above-mentioned technical objectives, the present invention is implemented through the following technical solution:

[0006] An EBR solvent comprising the following components in the following percentages:

[0007] Propylene glycol methyl ether acetate 95%–98%, propylene glycol methyl ether 2%–5%.

[0008] Preferably, the components in the EBR solvent are expressed in percentage as follows:

[0009] Propylene glycol methyl ether acetate 97%, propylene glycol methyl ether 3%.

[0010] Another object of the present invention is to provide a distillation preparation process for EBR solvent, comprising the following steps:

[0011] S1: Sedimentation filtration: After the waste liquid passes through the filter to remove solid waste, it enters the raw material sedimentation tank and is allowed to settle to remove solid impurities.

[0012] S2: Preliminary water removal: The supernatant after sedimentation enters the distillation tank, and the waste liquid is heated to make some of the water vapor form steam and enter the water collection tank after condensation. Water is continuously extracted from the bottom of the water collection tank, and a small amount of EBR active ingredients carried out from the upper layer are returned to the distillation tank.

[0013] S3: Feed: The primary waste liquid raw material mixed with the extractant is fed into the bottom of the distillation column, and the bottom heating device is turned on;

[0014] S4: Water Removal: After the primary waste liquid raw material in the tower is heated, the extractant and the remaining water in the raw material first vaporize and enter the heat exchange condenser from the top of the tower; the condensed extractant and water enter the collection tank; the extractant and water are separated into layers in the collection tank, with the extractant concentrated in the upper layer and the water concentrated in the lower layer; then the water is discharged from the bottom of the collection tank.

[0015] S5: Extractant reflux: The upper layer of extractant is refluxed back into the distillation column for reuse;

[0016] S6: Extraction of extractant: Repeat S4 and S5 until the water content in the collection tank drops below 0.1% and the extractant content is greater than 99.9%.

[0017] Extractant is collected from the collection tank;

[0018] S7: Collect EBR solvent: Close the reflux line between the collection tank and the distillation column; increase the temperature to heat the EBR liquid in the distillation column; vaporize it and then enter the heat exchanger condenser from the top of the column;

[0019] The condensed EBR solution is collected in a storage tank.

[0020] Preferably, the heating temperature of the distillation tank in S2 is controlled at 90-110°C;

[0021] When the primary waste liquid raw material reaches 80% to 90% in the distillation tank, it begins to be fed into the distillation column.

[0022] Preferably, the heating temperature of the tower in S4 is controlled at 100-120°C.

[0023] Preferably, the reflux ratio in S5 is controlled at 2 to 5:1.

[0024] Preferably, when the reflux ratio in S6 is close to 0.99:1, after the last extraction agent vapor is exhausted, the reflux pipeline valve between the collection tank and the distillation column is closed, and the pipeline valve between the storage tank and the distillation column is opened.

[0025] Preferably, the heating temperature of the column in S7 is controlled to be increased to 150-160°C, so that both PGMEA and PGME in the EBR solution are vaporized.

[0026] Preferably, the extractant comprises one of toluene, xylene, benzyl alcohol, and cyclohexane.

[0027] The beneficial effects of this invention are:

[0028] The EBR solvent provided by this invention includes two components, PGMEA and PGME. When the two components are mixed according to the ratio of this invention, they can achieve the best cleaning effect on the photoresist on the back and edge of the wafer.

[0029] This invention provides a method for purifying EBR solvent from diluted waste liquid. The method uses batch distillation technology to remove water from the waste liquid in batches, leaving EBR solvent with higher purity. The reflux ratio during the distillation process is controlled to improve the purity of the recovered EBR solvent.

[0030] Before entering the distillation column for batch distillation, some of the water is removed by conventional distillation in the distillation tank by controlling the temperature, thus shortening the time required to obtain the product through subsequent batch distillation. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the distillation preparation process of the EBR solvent of the present invention;

[0033] Figure 2 This is a flowchart of the distillation preparation process of the EBR solvent of the present invention.

[0034] In the attached diagram, the components represented by each number are:

[0035] 1-Distillation tank, 2-Distillation column, 3-Heat exchanger, 4-Collection tank, 5-Storage tank, 6-Water collection tank. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0037] Example 1

[0038] This embodiment provides an EBR solvent, comprising the following components in the following percentages:

[0039] Propylene glycol methyl ether acetate 97%, propylene glycol methyl ether 3%.

[0040] Preparation of EBR cleaning solution: Take a measured amount of EBR solvent and mix it thoroughly with water, the ratio of EBR solvent to water is 1:1; pour the prepared EBR cleaning solution into a spray bottle;

[0041] After soft baking the photoresist raised at the wafer edge, spray EBR cleaning solution evenly onto the surface of the photoresist raised at the wafer edge, being careful not to spray it into the effective area of ​​the photoresist; after spraying, let it stand for 5-10 minutes to allow the EBR cleaning solution to fully contact and react with the photoresist; then clean and wipe the wafer edge clean; observe and record the change in the thickness of the photoresist film at the wafer edge after cleaning.

[0042] Comparative Example 1

[0043] This comparative example provides an EBR solvent comprising the following components in the following percentages:

[0044] Propylene glycol methyl ether acetate 95%, propylene glycol methyl ether 5%.

[0045] Preparation of EBR cleaning solution: According to the EBR solvent composition ratio of this comparative example, take an equal amount of EBR solvent and water as in Example 1 and mix them thoroughly. The ratio of EBR solvent to water is also 1:1. Pour the prepared EBR cleaning solution into a spray bottle.

[0046] After soft baking the photoresist raised at the wafer edge, spray EBR cleaning solution evenly onto the surface of the photoresist raised at the wafer edge, being careful not to spray it into the effective area of ​​the photoresist; after spraying, let it stand for 5-10 minutes to allow the EBR cleaning solution to fully contact and react with the photoresist; then clean and wipe the wafer edge clean; observe and record the change in the thickness of the photoresist film at the wafer edge after cleaning.

[0047] Comparative Example 2

[0048] This comparative example provides an EBR solvent comprising the following components in the following percentages:

[0049] Propylene glycol methyl ether acetate 98%, propylene glycol methyl ether 2%.

[0050] Preparation of EBR cleaning solution: According to the EBR solvent composition ratio of this comparative example, take an equal amount of EBR solvent and water as in Example 1 and mix them thoroughly. The ratio of EBR solvent to water is also 1:1. Pour the prepared EBR cleaning solution into a spray bottle.

[0051] After soft baking the photoresist raised at the wafer edge, spray EBR cleaning solution evenly onto the surface of the photoresist raised at the wafer edge, being careful not to spray it into the effective area of ​​the photoresist; after spraying, let it stand for 5-10 minutes to allow the EBR cleaning solution to fully contact and react with the photoresist; then clean and wipe the wafer edge clean; observe and record the change in the thickness of the photoresist film at the wafer edge after cleaning.

[0052] Table 1 Record of Photoresist Cleaning Effect on Wafer Edge Ripples

[0053]

[0054] Conclusion Analysis: From the recorded data in Table 1, it can be concluded that the initial photoresist thickness at the wafer edge was 100 μm in all three experimental groups. The EBR solvent to water ratio in the EBR cleaning solution was 1:1 in all three groups, the concentration of the EBR cleaning solution was the same, and the cleaning reaction time was the same in all three groups. After cleaning the raised photoresist at the wafer edge using the EBR cleaning solution prepared with the EBR solvent ratio in Example 1, the thickness of the raised photoresist at the edge was only 0.52 μm. The EBR solvent ratio prepared in Comparative Example 1... After cleaning the photoresist protruding at the wafer edge with EBR cleaning solution, the thickness of the protruding photoresist was 2.58 μm; after cleaning the protruding photoresist at the wafer edge with EBR cleaning solution prepared according to the EBR solvent ratio in Comparative Example 2, the thickness of the protruding photoresist was 3.05 μm; therefore, Example 1 completed the photoresist dissolution and cleaning with a thickness of 99.48 μm; Comparative Example 1 completed the photoresist dissolution and cleaning with a thickness of 97.42 μm; and Comparative Example 2 completed the photoresist dissolution and cleaning with a thickness of 96.95 μm.

[0055] It is evident that, with the same EBR cleaning solution concentration and the same reaction time, the EBR cleaning solution prepared using the EBR solvent ratio in Example 1 has a significantly better cleaning effect than Comparative Example 1 and Comparative Example 2.

[0056] Example 2

[0057] like Figure 1 As shown in the schematic diagram, this embodiment provides a distillation preparation process for EBR solvent, including the following steps:

[0058] S1: Sedimentation filtration: After the waste liquid passes through the filter to remove solid waste, it enters the raw material sedimentation tank and is allowed to settle to remove solid impurities.

[0059] S2: Preliminary water removal: The supernatant after sedimentation enters the distillation tank. Considering the different altitudes and boiling points, the waste liquid is heated at a temperature of 90-110°C. In this embodiment, the supernatant can be heated at 110°C, so that some of the water in the supernatant forms steam and is discharged into the water collection tank after condensation, thus obtaining the primary waste liquid raw material. Water is continuously collected from the bottom of the water collection tank, and a small amount of EBR active ingredients carried out from the upper layer are returned to the distillation tank.

[0060] When the liquid level in the distillation tank reaches 80% after initial dehydration, feed is started into the distillation column;

[0061] S3: Feed: The primary waste liquid raw material mixed with the extractant is fed into the bottom of the distillation column, and the bottom heating device is turned on;

[0062] In this embodiment, toluene is used as the extractant; the primary waste liquid raw material mainly contains propylene glycol methyl ether acetate (PGMEA), propylene glycol methyl ether (PGME) and water; after adding toluene, the toluene and water are mixed and can boil and vaporize at the same or similar temperature, thereby achieving the purpose of removing water.

[0063] S4: Dehydration: The tower bottom is heated to 100°C. This temperature ensures that toluene and water vaporize simultaneously, but does not reach the boiling points of PGMEA and PGME. The toluene and water vapor mixture enters the heat exchange condenser from the top of the tower. After condensation, the mixed vapor mixture forms a mixed condensate that enters the collection tank.

[0064] Because toluene and water are immiscible, toluene concentrates in the upper layer and water concentrates in the lower layer in the collection tank; water is discharged from the bottom of the collection tank into the water collection tank.

[0065] S5: Extractant reflux: The toluene in the upper part of the collection tank is refluxed back into the distillation column for reuse; during this reflux process, the reflux ratio needs to be controlled at 3:1; that is, 3 parts of toluene are refluxed and 1 part of the mixed vapors are discharged; ensure that a sufficient amount of toluene is refluxed back into the distillation column to mix with water, and ensure that sufficient water is carried out after the two are azeotropically; shorten the drainage time and carry out sufficient water, so that the less water in the PGMEA and PGME mixed solvent, the higher the purity in the later purification.

[0066] S6: Extraction of Extractant: Repeat steps S4 and S5 multiple times, gradually reducing the water content in the liquid within the distillation tank; until the water content in the collection tank drops below 0.1%, the extractant content is greater than 99.9%, and the reflux ratio is close to 0.99:1, indicating that the water in the tank has been completely removed; the liquid exiting from the top of the distillation tank is toluene vapor; at this point, the heating temperature needs to be increased to 110°C to allow the toluene to vaporize separately and exit from the distillation tank, condense, and reach the collection tank to collect the toluene solution;

[0067] S7: Collect EBR solvent: After the toluene in the distillation tank is drained, close the reflux line between the collection tank and the distillation column; raise the heating temperature of the column bottom to 150-160°C; this temperature can cause both PGMEA and PGME in the distillation column to vaporize and be discharged from the top of the column. After passing through the heat exchanger, the condensate of the mixture of PGMEA and PGME is collected in the storage tank, thus obtaining the EBR solvent product.

[0068] Purity testing:

[0069] The purity of EBR solvent was determined by gas chromatography.

[0070] 1) Take 10 ml of the EBR solvent prepared according to the distillation preparation process provided in Example 2, add an appropriate amount of internal standard solution, and mix well;

[0071] 2) Inject the mixed sample into the GC chromatograph using an autosampler;

[0072] 3) Set appropriate chromatographic column and carrier gas flow rate, and adjust injection volume and discharge volume;

[0073] 4) Start the chromatograph, analyze the results, and record them.

[0074] Results analysis:

[0075] Chromatographic analysis of the chromatogram showed that the content of PGMEA in the EBR solvent sample reached 97.41%, and the content of PGME reached 2.48%. The combined purity of the two components reached 99.89%, achieving a high recovery and purification rate.

[0076] Example 3

[0077] In this embodiment, the preliminary dehydration step in the distillation tank is omitted, and the waste liquid is directly introduced into the distillation column for direct distillation; the remaining steps are the same as in the previous embodiment, as follows:

[0078] S1: Sedimentation filtration: After the waste liquid passes through the filter to remove solid waste, it enters the raw material sedimentation tank and is allowed to settle to remove solid impurities.

[0079] S2: Feed: The primary waste liquid raw material mixed with the extractant is fed into the bottom of the distillation column, and the bottom heating device is turned on;

[0080] In this embodiment, toluene is used as the extractant; the primary waste liquid raw material mainly contains propylene glycol methyl ether acetate (PGMEA), propylene glycol methyl ether (PGME) and water; after adding toluene, the toluene and water are mixed and can boil and vaporize at the same or similar temperature, thereby achieving the purpose of removing water.

[0081] S3: Dehydration: The tower bottom is heated to 100°C. This temperature ensures that toluene and water vaporize simultaneously, but does not reach the boiling points of PGMEA and PGME. The mixed vaporized product of toluene and water enters the heat exchange condenser from the top of the tower. After condensation, the mixed vaporized product forms a mixed condensate that enters the collection tank.

[0082] Because toluene and water are immiscible, toluene concentrates in the upper layer and water concentrates in the lower layer in the collection tank; water is discharged from the bottom of the collection tank into the water collection tank.

[0083] S4: Extractant reflux: The toluene in the upper part of the collection tank is refluxed back into the distillation column for reuse; during this reflux process, the reflux ratio needs to be controlled at 3:1; that is, 3 parts of toluene are refluxed and 1 part of the mixed vapors are discharged; ensure that a sufficient amount of toluene is refluxed into the distillation column to mix with water, and ensure that sufficient water is carried out after the two are azeotropically; shorten the drainage time and carry out a sufficient amount of water at the same time, so that the less water in the PGMEA and PGME mixed solvent, the higher the purity in the later purification.

[0084] S5: Extraction of Extractant: Repeat steps S3 and S4 multiple times, gradually reducing the water content in the liquid within the distillation tank; until the water content in the collection tank drops below 0.1%, the extractant content is greater than 99.9%, and the reflux ratio is close to 0.99:1, indicating that the water in the tank has been completely removed; the liquid exiting from the top of the distillation tank is toluene vapor; at this point, the heating temperature needs to be increased to 110°C to allow the toluene to vaporize separately and exit from the distillation tank, condense, and reach the collection tank to collect the toluene solution;

[0085] S6: Collect EBR solvent: After the toluene in the distillation tank is drained, close the reflux line between the collection tank and the distillation column; raise the heating temperature of the column bottom to 150-160°C; this temperature can cause both PGMEA and PGME in the distillation column to vaporize and be discharged from the top of the column. After passing through the heat exchanger, the condensate of the mixture of PGMEA and PGME is collected in the storage tank, thus obtaining the EBR solvent product.

[0086] Results analysis:

[0087] Compared to Example 1, the direct distillation method for filtered waste liquid in this embodiment requires 5 to 7 more reflux operations to achieve the same water removal effect without replenishing the extractant during the process. This is because, in addition to the high water content at the beginning of distillation in this embodiment, each reflux results in some loss of extractant. Therefore, the more refluxes are performed, the less extractant remains in the later stages of reflux, which in turn requires more repeated refluxes to achieve the goal of removing as much water as possible.

[0088] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0089] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. An EBR solvent, characterized in that, It includes the following components in the following percentages: 97% propylene glycol methyl ether acetate and 3% propylene glycol methyl ether.

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