Cassette cleaning process and cleaning device thereof

Abstract

The invention relates to a cassette cleaning process and a cleaning device thereof. The invention discloses a cassette cleaning process which is used for sequentially performing spraying, ultrasonic cleaning and bubbling rinsing procedures on a cassette. Wherein in the bubbling rinsing step, gas with a certain flow rate is filled into liquid to form tiny bubbles, so that tiny particles falling off in the ultrasonic cleaning step are taken away. The cassette cleaning process has the advantages that tiny particles which fall off during ultrasonic cleaning and then are attached to the surface layer are timely and effectively peeled off again and discharged, secondary attachment is avoided, and the cleaning efficiency and effect are improved; and large-size particles and residual chemical substances in the cassette are cleaned through spraying, so that various types of pollutants are cleaned.

Description

Technical Field

[0001] The invention relates to the field of cleaning, and in particular to a dark box cleaning process and a cleaning device thereof. Background Art

[0002] In the field of photolithography, silicon wafers, wafers, mask substrates and mask plates coated with photoresist need to be sealed and shielded when leaving the yellow light area. This sealed and shielded treatment generally uses plastic boxes to package and seal the products to be processed, otherwise the products will be at risk of being scrapped due to exposure. The plastic box that packages the products is the dark box. After long-term use, the dark box will be contaminated to varying degrees due to friction between the edge of the product and the positioning point of the packaging box, dust accumulation in the air in the factory, dust generated by vibration and impact during moving, and pollution from manual contact.

[0003] The existing cassette cleaning process mainly uses ultrasonic cleaning. Ultrasonic cleaning uses the cavitation effect of ultrasound in liquid to generate a large number of tiny bubbles in the liquid. The bubbles grow rapidly in the negative pressure area and close in the positive pressure area, instantly generating high-pressure shock waves, which cause the pollutants on the cassette to fall off and then be discharged by water.

[0004] However, the finished product corresponding to the product after the dark box is cleaned and sealed and shielded by the existing dark box cleaning process still has the probability of abnormalities such as connecting lines or black spots, and the yield rate is low, resulting in a large waste of resources. Summary of the invention

[0005] Based on this, the object of the present invention is to provide a dark box cleaning process, which can clean the dark box more thoroughly, thereby reducing the probability of abnormalities such as connecting lines or black spots appearing in the finished product and improving the yield rate.

[0006] The present invention provides a dark box cleaning process, which comprises spraying, ultrasonic cleaning and bubbling rinsing processes for the dark box in sequence; wherein, the bubbling rinsing forms tiny bubbles by filling a gas with a certain flow rate into a liquid to take away the tiny particles detached during the ultrasonic cleaning.

[0007] Compared with the prior art, the dark box cleaning process of the present invention utilizes the tiny bubbles formed by the gas of a certain flow rate rushing into the liquid to peel off and carry away the tiny particles, and timely and effectively peel off and discharge the tiny particles that fall off and then adhere to the surface layer after ultrasonic cleaning, so as to avoid reattachment, thereby improving the cleaning efficiency and effect. At the same time, this process also cleans the large-sized particles and residual chemicals in the dark box by spraying, and cleans various types of pollutants.

[0008] Furthermore, the gas used for the bubbling rinsing is nitrogen, and its flow rate is 5-10 LPM. Using widely used nitrogen as the bubbling gas reduces costs and is pollution-free. Using nitrogen with a flow rate of 5-10 LPM can ensure that the tiny particles are fully peeled off and discharged, and reduce costs.

[0009] Furthermore, the ultrasonic cleaning uses 1-5 MHz ultrasonic waves.

[0010] Furthermore, during the ultrasonic cleaning and bubbling rinsing, the dark box is rotated at a speed of 5-20 rpm. By rotating the dark box during the cleaning process, the water flow rate is increased and the cleaning effect is enhanced.

[0011] Furthermore, the drying is drying with hot nitrogen.

[0012] Furthermore, the temperature of the hot nitrogen is 80-100° C. Using hot nitrogen at 80-100° C. can achieve a better drying effect without causing deformation due to excessive temperature.

[0013] Based on the same inventive concept, the present invention also provides a dark box cleaning device used in the above-mentioned dark box cleaning process, which includes a nozzle, a cleaning tank, an ultrasonic generator and a gas delivery pipe; the dark box is placed in the cleaning tank; the nozzle sprays the dark box and injects water into the cleaning tank; the ultrasonic generator generates ultrasonic waves to ultrasonically clean the dark box; the gas delivery pipe fills the cleaning tank with gas at a certain flow rate to form tiny bubbles to take away tiny particles detached during the ultrasonic cleaning.

[0014] Furthermore, the gas delivered by the gas delivery pipe is nitrogen, and its flow rate is 5-10 LPM. The dark box and the water flow are driven to rotate by the rotating table, so as to further improve the cleaning and rinsing efficiency and effect.

[0015] Furthermore, the ultrasonic generator emits 1-5 MHz ultrasonic waves.

[0016] Furthermore, it also includes a rotating table on which the cleaning tank is installed; the rotating table drives the cleaning tank to rotate; when the ultrasonic generator and the gas delivery pipe are working, the rotating table rotates at a speed of 5-20rpm.

[0017] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural diagram of the dark box cleaning device of the present invention;

[0019] Figure 2 The figure is a flow chart of the dark box cleaning process of the present invention. DETAILED DESCRIPTION

[0020] The inventor studied the causes of the abnormalities of connecting lines and black spots in the finished product and found that the cause was the presence of tiny particles less than one micron in the dark box. These tiny particles fell on the silicon wafer, wafer, mask substrate or mask plate, affecting the subsequent photolithography process, resulting in the abnormalities of connecting lines and black spots in the photolithography product. In order to completely remove these tiny particles, the prior art often increases the ultrasonic power or increases the number of cleaning times. However, the inventor conducted further research on the existing dark box cleaning method and found that the above-mentioned tiny particles can all fall off during ultrasonic cleaning. However, the traditional overflow or rapid drainage method cannot effectively discharge the detached tiny particles, causing the tiny particles to re-attach to the dark box, resulting in poor cleaning effect. Based on this, the inventor added a cleaning process of bubbling rinsing after the existing ultrasonic cleaning, by filling a certain flow rate of gas into the liquid to form a large number of tiny bubbles to take away the above-mentioned tiny particles, and peel off the tiny particles that may be attached, so as to achieve effective removal of the tiny particles.

[0021] Furthermore, the inventors also studied various parameters in the improved cleaning process, among which, the ultrasonic frequency in ultrasonic cleaning is 1-5MHz, the nitrogen flow rate of 2-10LPM is used in bubbling rinsing, and the dark box rotates at a speed of 5-20rpm, which are the optimal parameters in the process of cleaning the dark box using this process.

[0022] Based on this, the inventor has also designed a dark box cleaning device that adopts this process for the dark box cleaning process.

[0023] Please refer to Figure 1 , Figure 1 1 is a structural diagram of a cassette cleaning device of the present invention. The cassette cleaning device of the present invention comprises a housing, a rotating table 10, a cleaning tank 20, a nozzle 30, an ultrasonic generator 40 and a gas delivery pipe 50. The rotating table 10, the cleaning tank 20, the nozzle 30, the ultrasonic generator 40 and the gas delivery pipe 50 are all installed in the housing.

[0024] Specifically, a cleaning cavity is provided in the shell, and a top cover is provided on the top of the shell, and the top cover has an air filtering function.

[0025] The rotating table 10 is located in the cleaning chamber and is driven by a motor to rotate along a center point.

[0026] The cleaning tank 20 is arranged in the cleaning chamber, with a certain gap between it and the inner wall of the cleaning chamber. The cleaning tank 20 is also installed on the rotating platform 10 and rotates with the rotating platform 10. A tray 21 is arranged in the middle of the cleaning tank 20, and a plurality of water leakage holes are arranged on the tray 21. The dark box to be cleaned is placed on the tray 21. The cleaning tank 20 is also provided with a drain port that can be opened and closed.

[0027] The spray mechanism 30 includes an upper nozzle 31 and a lower nozzle 32. The upper nozzle 31 is disposed above the cleaning tank 20 to spray liquid into the cleaning tank 20. The lower nozzle 32 is disposed below the sieve tray 21 in the cleaning tank 20 to spray liquid onto the tray 21.

[0028] The ultrasonic generator 40 is installed on the inner surface of the side wall of the cleaning tank 20 to generate ultrasonic waves.

[0029] The gas delivery pipe 50 passes through the rotation center of the rotating table 10 and the cleaning tank 20 from the outside and enters the cleaning tank 20 to deliver gas into the cleaning tank 20 .

[0030] See also Figure 2 , Figure 2 The flowchart of the dark box cleaning process of the present invention is shown in FIG. A dark box cleaning process of the present invention comprises:

[0031] S1: spray;

[0032] S2: ultrasonic cleaning;

[0033] S3: Bubble rinsing;

[0034] The spray mechanism 30 in the dark box cleaning device performs the step S1 spraying in this cleaning process. Specifically, before performing the step S1 spraying, the dark box is first scrubbed with a 3%-10% isopropyl alcohol (IPA) solution. After the scrubbing is completed, the dark box is placed on the tray 21 of the cleaning tank 20 through the top cover of the dark box cleaning device, and the dark box cleaning device is started. At this time, the drain port of the cleaning tank 20 is opened, and the upper nozzle 31 and the lower nozzle 32 spray 0.2-0.4MPa pure water, wherein the upper nozzle 31 sprays the dark box from above, and the lower nozzle 32 sprays the dark box from below. At the same time, the rotating table 10 drives the cleaning tank and the dark box to rotate at a speed of 20-50rpm. After the spraying process is completed, the drain port of the cleaning tank 20 is closed, and the spray mechanism 30 continues to fill water into the cleaning tank 20 and maintain overflow. Preferably, 5% IPA solution is used for scrubbing during the scrubbing process; during the S1 spraying process, the nozzle 30 sprays 0.35 MPa pure water, and the rotation speed of the rotating table 10 is 30 rpm.

[0035] The ultrasonic generator 40 in the cassette cleaning device performs the ultrasonic cleaning process in step S2 of the cleaning process. Specifically, when overflow is formed in the cleaning tank 20, the speed of the rotating table 10 becomes 5-20rpm; the ultrasonic generator 40 emits 1-5MHz ultrasonic waves, and the ultrasonic waves generate a large number of tiny bubbles in the pure water due to the cavitation effect. The bubbles grow rapidly in the negative pressure area and close in the positive pressure area, instantly generating high-pressure shock waves, causing the tiny particles on the cassette to fall off. After the ultrasonic cleaning is completed, the ultrasonic generator 40 stops emitting ultrasonic waves, and the spray mechanism 30 continues to inject water. Preferably, the ultrasonic frequency is 2MHz, and the rotation speed of the cassette is 10rpm.

[0036] The gas delivery pipe 50 in the dark box cleaning device performs the bubbling rinse in step S3 of this cleaning process. Specifically, after the ultrasonic cleaning process is completed, the rotation speed of the rotating table 10 remains unchanged; the gas delivery pipe 50 delivers gas to the inside of the cleaning tank 20, and the gas is injected into the liquid to form tiny bubbles, which continue to expand in the liquid and eventually burst. The tiny shock waves generated when the bubbles burst release energy, which will peel off the tiny particles that may be attached to the surface and be taken away together with the remaining detached tiny particles. After the bubbling rinse is completed, the spray mechanism 30 stops injecting water, the drain port of the cleaning tank 20 is opened, and after the water in the cleaning tank 20 is drained, the rotating table 10 rotates at a speed of 100-300rpm for drying. Preferably, the gas is nitrogen, and the delivery flow rate of the nitrogen is 5LPM; when drying, the rotating table 10 rotates at a speed of 200rpm.

[0037] Furthermore, the dark box cleaning process of the present invention also includes: a drying process after bubbling rinsing. After the cleaning process is completed, the cleaned dark box is taken out from the top cover of the dark box cleaning device for drying. In this embodiment, hot nitrogen is used for drying. The cleaned dark box is transferred to a hot nitrogen drying device, and hot nitrogen with a temperature of 80-100°C is used for blowing for 100-300S, and the dark box is rotated at a speed of 50-100rpm during hot nitrogen drying. Preferably, the hot nitrogen temperature is 90°C, the blowing time is 200S, and the rotation speed of the dark box is 50rpm.

[0038] Furthermore, the dark box after drying is inspected. The inspection is to visually check whether there are any pollutants remaining in the dark box under 120,000 lux light to judge the cleaning condition. If no pollutants remain, the dark box is sprayed with an antistatic agent.

[0039] For the cassettes cleaned by this cassette cleaning method, a particle counter is used to measure the number of particles generated by shaking before and after cleaning, and the ratio of the number of tiny particles before cleaning to the number of tiny particles after cleaning is used to represent the residual tiny particles. Under the cleaning process using different ultrasonic frequencies and bubbling rates, the residual amount of tiny particles in the cassette is shown in the following table:

[0040]

[0041] The cleaning effect of the cassette using the cassette cleaning process of this embodiment was tested, and the residual amount of tiny particles of the cassette under different process parameter combinations in the parameter range of 1-5MHz ultrasonic frequency and 2-10LPM bubbling rate was tested respectively. The test results show that in the ultrasonic frequency range of 1-5MHz and the bubbling rate range of 2-10LPM, when the bubbling rate is kept constant, as the ultrasonic frequency increases, the cleaning effect of the cassette first increases and then weakens, and the best cleaning effect is achieved when the frequency is 2MHz; referring to the data when the bubbling rate is 5LPM, it can be seen that when the ultrasonic frequency is 2MHz, the residual amount of tiny particles is the least, which is 1% of the number of tiny particles before cleaning, and the residual amount of tiny particles is much lower than 12% when the ultrasonic frequency is 1MHz and 6% when the ultrasonic frequency is 5MHz. When the ultrasonic frequency is kept constant, as the frequency of the bubbling rate increases, the cleaning effect of the dark box also shows a trend of first strengthening and then weakening, and the best cleaning effect is achieved when the rate is 5LPM; referring to the data when the ultrasonic frequency is 2MHz, it can be seen that when the bubbling rate is 5LPM, the residual amount of tiny particles is the least, which is 1% of the number of tiny particles before cleaning, and the residual amount of tiny particles is much lower than 6% when the bubbling rate is 2LPM and 7% when the bubbling rate is 10LPM. This proves that when the ultrasonic frequency is 2MHz and the bubbling rate is 5LPM, the cleaning effect of this cleaning process is the best, and the residual amount of tiny particles in the dark box is only 1% of the number of tiny particles before cleaning.

[0042] Comparative Example:

[0043] If the present cassette cleaning process is not used in the cassette cleaning process, and only ultrasonic waves are used to clean the cassette, the amount of residual microparticles in the cassette is as shown in the following table:

[0044] Ultrasonic frequency (MHz) Residual amount of microparticles (%) 5 32％

[0045] It can be seen from the comparative example that when only 5MHz frequency ultrasonic waves are used for cleaning, the amount of residual tiny particles in the dark box is 32% of the amount of tiny particles before cleaning, and the residual tiny particles are large, and the cleaning effect is poor.

[0046] Compared with the comparative example, the cleaning process used in this embodiment can clean the dark box more effectively, which is reflected in the process of using 1MHz ultrasonic wave and 2LPM bubbling rate and using 5MHz ultrasonic wave and 10LPM bubbling rate. The residual amount of tiny particles in the dark box is 20% and 11% respectively, and the cleaning effect is better than the comparative example, indicating that there is a better cleaning effect in the process range of 1-5MHz ultrasonic frequency and 2-10LPM bubbling rate. At the same time, under the same 5MHz ultrasonic wave, the use of 2-10LPM bubbling rinsing has a significant effect, and the residual amount of tiny particles is reduced by 62.5%-81.25%, which shows that bubbling rinsing has a significant effect on the cleaning of tiny particles on the dark box. Therefore, it can be seen that the effect of the dark box cleaning process in this embodiment is significantly improved compared with the process of only using ultrasonic cleaning.

[0047] Compared with the prior art, the present invention utilizes the tiny bubbles formed by the gas at a certain flow rate rushing into the liquid to peel off and carry away the tiny particles, and timely and effectively peel off and discharge the tiny particles that fall off and then adhere to the surface layer after ultrasonic cleaning, avoiding reattachment, thereby improving the cleaning efficiency and effect. At the same time, this process also cleans large-sized particles and residual chemicals in the dark box by spraying, and cleans various types of pollutants.

[0048] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. The singular forms of "a", "said" and "the" used in the embodiments of the present application and the claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that, unless otherwise specified, "multiple" refers to two or more; the terms "first", "second", "third", etc. are only used to distinguish, rather than to describe a specific order or sequence, and cannot be understood as indicating or implying relative importance. The term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items. When the above description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of the present application, for those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0049] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and the present invention is also intended to include these modifications and modifications.

Claims

1. A dark box cleaning process, characterized in that: The dark box is subjected to spraying, ultrasonic cleaning and bubbling rinsing processes in sequence; wherein, the bubbling rinsing forms tiny bubbles by filling a gas at a certain flow rate into the liquid to take away the tiny particles detached during the ultrasonic cleaning.

2. A dark box cleaning process according to claim 1, characterized in that: The gas used for the bubbling rinse is nitrogen, and its flow rate is 5-10 LPM.

3. A dark box cleaning process according to claim 2, characterized in that: The ultrasonic cleaning adopts 1-5 MHz ultrasonic waves.

4. A dark box cleaning process according to claim 3, characterized in that: During the ultrasonic cleaning and bubbling rinsing, the dark box is rotated at a speed of 5-20 rpm.

5. A dark box cleaning process according to claim 4, characterized in that: The method also includes a drying process after bubbling and rinsing; the drying process is performed by blowing with hot nitrogen.

6. A dark box cleaning process according to claim 5, characterized in that: The temperature of the hot nitrogen is 80-100° C., and the drying time is 100-300 seconds.

7. A dark box cleaning device used in the dark box cleaning process of claim 1, characterized in that: It comprises a spray mechanism, a cleaning tank, an ultrasonic generator and a gas delivery pipe; the cleaning tank contains the dark box; the spray mechanism sprays the dark box and injects water into the cleaning tank; the ultrasonic generator generates ultrasonic waves to ultrasonically clean the dark box; the gas delivery pipe fills the cleaning tank with gas at a certain flow rate to form tiny bubbles to take away the tiny particles detached during the ultrasonic cleaning.

8. A cassette cleaning device according to claim 7, characterized in that: The gas transported by the gas delivery pipe is nitrogen, and its flow rate is 5-10LPM.

9. A cassette cleaning device according to claim 8, characterized in that: The ultrasonic generator generates 1-5 MHz ultrasonic waves.

10. A cassette cleaning device according to claim 9, characterized in that: It also includes a rotating table on which the cleaning tank is installed; the rotating table drives the cleaning tank to rotate; when the ultrasonic generator and the gas delivery pipe are working, the rotating table rotates at a speed of 5-20rpm.

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