Cleaning method for shield component

Abstract

The invention relates to the technical field of semiconductor equipment cleaning, and particularly discloses a shield component cleaning method which comprises the following steps of pre-protection, acid leaching, water leaching, gravity sand blasting, high-pressure water washing, ultrasonic cleaning, drying and packaging. In the pre-protection step, the bottom of the shield part is protected by using an acid and alkali resistant adhesive tape, and the four layers of PE bags are pressed by using a cover matched with the shield part and are pressed on the inner edge of the cover; the volume ratio of nitric acid to hydrofluoric acid in the acid leaching step is (5-7): 1; and in the gravity sand blasting step, aluminum oxide sand is adopted for carrying out surface sand blasting on the shield component, and the sand blasting pressure is 3-4 kg / cm < 2 >. The method for cleaning the shield component has the advantages of being short in film removing period, high in cleaning efficiency, safe, reliable and the like, the basic functions of the shield component can be effectively recovered, and repeatability and reliability of the PVD technology are guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor equipment cleaning, in particular to a cleaning method of a shield component. BACKGROUND

[0002] In the field of semiconductor manufacturing, physical vapor deposition (PVD) technology is one of the key processes for preparing metal interconnection lines in integrated circuits. In a radio frequency (RF) titanium (Ti) PVD device, the shield (baffle / shield ring) in the process cavity is one of the core spare parts, which mainly functions to protect the cavity wall from titanium sputtering contamination during the deposition process, ensuring the purity and stability of the process; aluminum or aluminum alloy has good thermal conductivity and mechanical processing performance, so it is often used as the manufacturing substrate of the component. During the PVD process, a layer of titanium and titanium compound film will inevitably be deposited on the surface of the shield component, and when the film accumulates to a certain thickness, it will cause particle contamination, arc discharge and other problems, seriously affecting the quality and uniformity of film deposition, and ultimately leading to a decrease in product yield. Therefore, the shield component must be cleaned regularly to completely remove the titanium film on the surface and restore its function, ensuring the repeatability and reliability of the PVD process.

[0003] Currently, the conventional cleaning method for aluminum-based shield components in the industry mainly involves: first, using a mixed solution of ammonia and hydrogen peroxide for overall immersion, and then performing post-processing through stripping sandblasting, finally achieving cleaning; however, in actual application, the above method still has the following problems: first, the film removal efficiency is low and the cleaning period is too long, the entire immersion film removal process usually lasts for more than 7 days, which seriously restricts the turnover rate of key spare parts and increases the spare parts inventory and cost of the production line. Second, the corrosion risk of the substrate is high, that is, the aluminum substrate is exposed to an ammonia and hydrogen peroxide environment for a long time, and uniform or non-uniform corrosion reactions are likely to occur on its surface, which not only destroys the original smoothness of the surface of the shield component and generates by-products that are difficult to remove, but also shortens the service life of the component, greatly increasing the production cost. Third, the deformation rate of the component is high, the pressure control during the stripping sandblasting process is not accurate, and the impact on the large-area, thin-walled aluminum shield component is too strong, which easily leads to physical deformation such as warping or sagging, and the deformation rate of the shield component is as high as 80%, once the deformation occurs, the component cannot be precisely fitted with the cavity, which may cause process abnormalities or even vacuum leakage of the cavity, resulting in huge economic losses. In summary, the cleaning method of "ammonia and hydrogen peroxide immersion + stripping sandblasting" used for the existing aluminum-based shield component cannot meet the requirements of modern semiconductor manufacturing for high precision, high efficiency and high reliability in terms of cleaning efficiency, cleaning quality and safety.

[0004] Therefore, it is urgent to develop a cleaning method with short film removal time, low corrosion probability of component surface and avoiding component deformation to meet the higher standard of core component maintenance for advanced semiconductor processes. SUMMARY

[0005] In order to overcome the problems of long film removal time, easy corrosion of substrate surface and easy deformation of substrate existing in the existing shield component cleaning method, the application provides a cleaning method of shield component.

[0006] The application provides a cleaning method of shield component, which adopts the following technical scheme: The cleaning method of shield component comprises the following steps: pre-protection, acid immersion, water immersion, gravity sand blasting, high-pressure water washing, ultrasonic cleaning, drying and packaging. In the pre-protection step, acid and alkali adhesive tape is used to protect the bottom of the shield component, and a cover matched with the shield component is used to press the 4-layer PE bag and is pressed on the inner edge of the cover. The acid immersion liquid used in the acid immersion step is nitric acid and hydrofluoric acid with a volume ratio of (5-7): 1. In the gravity sand blasting step, alumina sand material is used to sand blast the surface of the shield component, and the sand blasting pressure is 3-4 kg / cm 2 .

[0007] The application provides a cleaning method of RF Ti equipment shield component for PVD process. The method first adopts acid and alkali adhesive tape and PE bag to pre-protect the shield component, effectively preventing the bottom and inner edge of the shield component from being corroded. Then, nitric acid and hydrofluoric acid with a volume ratio of (5-7): 1 are used for acid immersion, thereby greatly shortening the removal time of the Ti film on the surface of the shield component, reducing the removal time from more than 7 days to within 30 minutes. Finally, gravity sand blasting is used instead of traditional stripping sand blasting with strong impact force, and the sand blasting pressure is controlled within the above range, effectively reducing the risk of substrate deformation, and reducing the condition of substrate deformation from more than 80% to less than 5%. In summary, the cleaning method of shield component provided by the application has the advantages of short film removal cycle, high cleaning efficiency, safety and reliability, solves the problems of long cleaning cycle, substrate corrosion and component deformation existing in the existing method, and provides strong support for stable operation and benefit improvement of semiconductor manufacturing equipment.

[0008] In some embodiments, the volume ratio of the nitric acid and the hydrofluoric acid can be (5-6): 1 or (6-7): 1.

[0009] In a specific embodiment, the volume ratio of the nitric acid and the hydrofluoric acid can also be 5: 1, 6: 1 or 7: 1.

[0010] In some implementations, the sandblasting pressure can be 3-3.5 kg / cm². 2 Or 3.5-4 kg / cm 2 .

[0011] In one specific implementation, the sandblasting pressure can also be 3 kg / cm². 2 3.5kg / cm 2 Or 4kg / cm 2 .

[0012] Optionally, the acid leaching time is 5-10 minutes.

[0013] Optionally, the concentration of the nitric acid is 65-70 v / v, and the concentration of the hydrofluoric acid is 48-50 v / v.

[0014] Optionally, in the high-pressure water washing step, the pressure of the high-pressure water gun is 120±10Psi, and the washing time is 2-4min.

[0015] Optionally, during the water washing process, the shield component is rotated once every 30 seconds, with each rotation being 90°.

[0016] Optionally, in the ultrasonic cleaning step, the ultrasonic frequency is 35-45kHz and the ultrasonic power density is 4-10W / in. 2 The ultrasonic cleaning time is 25-40 minutes.

[0017] Optionally, during the ultrasonic cleaning process, the shield component is rotated once every 10 minutes, with each rotation being 90°.

[0018] Optionally, the drying temperature is 130-160℃ and the time is 2-3 hours.

[0019] Optionally, after water immersion and ultrasonic cleaning, the shield components should be purged with high-purity nitrogen gas at a pressure of 30±5 Psi.

[0020] In summary, this application has the following beneficial effects: 1. The cleaning method for shield components provided in this application can shorten the cleaning time of shield components to within a few hours, greatly accelerate the recycling rate of spare parts, and significantly reduce the spare parts inventory and holding costs of the production line.

[0021] 2. The cleaning method for shield components provided in this application can effectively prevent the bottom and inner edge of the shield from being corroded in a strong acid environment, maintain the integrity of the shield components, and extend the service life of the components.

[0022] 3. The cleaning method for shield components provided in this application can control the deformation rate of shield components to below 5%, basically eliminating the risk of component deformation and scrap caused by the cleaning process, and ensuring the precision fit between the cleaned components and the process cavity. Attached Figure Description

[0023] Figure 1 These are images of the shield component and cover component in this application; Figure 2 This is a schematic diagram of the pre-protection and acid immersion operations in the cleaning method for shield components provided in this application. Detailed Implementation

[0024] This application provides a cleaning method for shield components in RF-Ti devices, comprising the following steps: (1) Pre-protection: First, check whether there is corrosion and deformation on the surface of the shield component; then use acid and alkali resistant tape to protect the bottom of the shield component, use the cover that matches the shield component to press down 4 layers of PE bag, press it on the inner edge of the cover, and cut off the excess PE bag.

[0025] (2) Acid immersion: Place the Teflon tank flat and ensure that there are no foreign objects at the bottom of the tank; after placing a layer of bubble wrap at the bottom of the tank, place the pre-protected shield component in the Teflon tank; inject the prepared nitric acid into the shield component to completely immerse it and soak for 5-10 minutes; the nitric acid is 65-70 v / v% nitric acid and 48-50 v / v% hydrofluoric acid in a volume ratio of (5-7):1.

[0026] (3) Water immersion: Remove the shield component from the Teflon tank, then remove the external protection of the shield component, and immerse the shield component in a pure water tank for 25-40 minutes, with the pure water overflowing; after immersion, use high-purity nitrogen to purge the surface of the component to remove water droplets, with the air gun pressure being 30±5Psi.

[0027] (4) Gravity blasting: The shield components are blasted with alumina abrasive at a pressure of 3-4 kg / cm². 2 .

[0028] (5) High-pressure water washing: Transfer the shield component to the high-pressure water washing chamber and rinse it with a high-pressure water gun for 2-4 minutes. The pressure of the high-pressure water gun is 120±10Psi. During the water washing process, rotate the shield component once every 30 seconds, rotating 90° each time.

[0029] (6) Ultrasonic Cleaning: Transfer the shield components to a Class 1000 cleanroom, then place the shield components into the Teflon tank of the ultrasonic cleaning tank. The Teflon tank is filled with pure water, which is in an overflow state. Perform ultrasonic cleaning for 25-40 minutes at an ultrasonic frequency of 35-45kHz and an ultrasonic power density of 4-10W / in. 2 During the ultrasonic cleaning process, the shield component was rotated once every 10 minutes, with each rotation being 90°. After ultrasonic cleaning, high-purity nitrogen was used to purge the surface of the component to remove water droplets, with the air gun pressure at 30±5 Psi.

[0030] (7) Drying and packaging: After nitrogen purging, the shield parts are transferred to a clean drying box, placed on two Teflon rods, and dried in a nitrogen environment at 130-160℃ for 2-3 hours. Then, they are naturally cooled to below 40℃ and taken out. Finally, they are transferred to a Class 100 clean room and vacuum-sealed with two layers of PE bags. Before packaging, the parts are purged as a whole with an air gun pressure of 30±5Psi to obtain the cleaned shield parts.

[0031] In this application, the components in the RF Ti equipment of the PVD process for shielded components are made of aluminum, model 6061; the acid and alkali resistant tape was purchased from Xincheng Changli; the alumina sand material is model WA46# and was purchased from Zibo Jinjiyuan; the raw materials, reagents, solvents, etc. used in this application can all be obtained commercially.

[0032] The present application will be further described in detail below with reference to embodiments, performance testing tests and accompanying drawings.

[0033] Example 1 Example 1 provides a cleaning method for shield components in RF-Ti devices, comprising the following steps: (1) Pre-protection: First, check whether there is corrosion and deformation on the surface of the shield component; then use acid and alkali resistant tape to protect the bottom of the shield component, use the cover that matches the shield component to press down 4 layers of PE bag, press it on the inner edge of the cover, and cut off the excess PE bag.

[0034] (2) Acid immersion: Place the Teflon tank flat and ensure that there are no foreign objects at the bottom of the tank; after placing a layer of bubble wrap at the bottom of the tank, place the pre-protected shield component in the Teflon tank; inject the prepared nitric acid into the shield component to completely immerse it and soak for 5 minutes; the nitric acid is 66v / v% nitric acid and 49v / v% hydrofluoric acid in a volume ratio of 6:1.

[0035] (3) Water immersion: Remove the shield component from the Teflon tank, then remove the external protection of the shield component, and immerse the shield component in a pure water tank for 30 minutes with the pure water overflowing; after immersion, use high-purity nitrogen to purge the surface of the component to remove water droplets, with the air gun pressure being 30Psi.

[0036] (4) Gravity blasting: The shield components are blasted with alumina abrasive at a pressure of 3.5 kg / cm². 2 .

[0037] (5) High-pressure water washing: Transfer the shield component to the high-pressure water washing chamber and rinse it with a high-pressure water gun for 2 minutes. The pressure of the high-pressure water gun is 120Psi. During the water washing process, rotate the shield component once every 30 seconds, rotating 90° each time.

[0038] (6) Ultrasonic Cleaning: Transfer the shield components to a Class 1000 cleanroom, then place the shield components into the Teflon tank of the ultrasonic cleaning tank. The Teflon tank is filled with pure water, which is in an overflow state. Perform ultrasonic cleaning for 30 minutes at an ultrasonic frequency of 40kHz and an ultrasonic power density of 6W / in. 2 During the ultrasonic cleaning process, the shield component was rotated once every 10 minutes, with each rotation being 90°. After ultrasonic cleaning, high-purity nitrogen was used to purge the surface of the component to remove water droplets, with the air gun pressure at 30 Psi.

[0039] (7) Drying and packaging: After nitrogen purging, the shield parts are transferred to a clean drying oven, placed on two Teflon rods, and dried in a nitrogen environment at 150°C for 2 hours. Then, they are naturally cooled to below 40°C and taken out. Finally, they are transferred to a Class 100 clean room and vacuum-sealed with two layers of PE bags. Before packaging, the parts are purged as a whole with an air gun pressure of 30Psi to obtain the cleaned shield parts.

[0040] Example 2 Example 2 provides a cleaning method for shield components in RF-Ti devices.

[0041] The difference between the above embodiment and Embodiment 1 is that the acid leaching solution used in the acid leaching step is 66v / v% nitric acid and 49v / v% hydrofluoric acid in a volume ratio of 5:1.

[0042] Example 3 Example 3 provides a cleaning method for shield components in RF-Ti devices.

[0043] The difference between the above embodiment and Embodiment 1 is that the acid leaching solution used in the acid leaching step is 66v / v% nitric acid and 49v / v% hydrofluoric acid in a volume ratio of 7:1.

[0044] Example 4 Example 4 provides a cleaning method for shield components in RF-Ti devices.

[0045] The difference between the above embodiment and Embodiment 1 is that the sandblasting pressure in the gravity sandblasting step is 3 kg / cm². 2 .

[0046] Example 5 Example 5 provides a cleaning method for shield components in RF-Ti devices.

[0047] The difference between the above embodiment and Embodiment 1 is that the sandblasting pressure in the gravity sandblasting step is 4 kg / cm². 2 .

[0048] Comparative Example 1 Comparative Example 1 provides a cleaning method for shield components in RF-Ti devices.

[0049] The difference between the above comparative example and Example 1 is that the acid leaching solution used in the acid leaching step is 66 v / v nitric acid and 49 v / v hydrofluoric acid in a volume ratio of 1:1.

[0050] Comparative Example 2 Comparative Example 2 provides a cleaning method for shield components in RF-Ti devices.

[0051] The difference between the above comparative example and Example 1 is that the acid leaching solution used in the acid leaching step is 66 v / v nitric acid.

[0052] Comparative Example 3 Comparative Example 3 provides a cleaning method for shield components in RF-Ti devices.

[0053] The difference between the above comparative example and Example 1 is that the acid leaching solution used in the acid leaching step is 49 v / v% hydrofluoric acid.

[0054] Comparative Example 4 Comparative Example 4 provides a cleaning method for shield components in RF-Ti devices.

[0055] The difference between the above comparative example and Example 1 is that the sandblasting pressure in the gravity sandblasting step is 5 kg / cm². 2 .

[0056] Comparative Example 5 Comparative Example 5 provides a cleaning method for shield components in RF-Ti devices.

[0057] The difference between the above comparative example and Example 1 is that the acid leaching step uses a mixed solution of 20% ammonia and 40% hydrogen peroxide with a volume ratio of 1:4; the leaching time is 7 days; and the gravity sandblasting is replaced with WA60# white corundum abrasive for peeling sandblasting.

[0058] Performance testing The shield components with a surface containing Ti deposits of 800 μm thickness were cleaned according to the cleaning methods provided in Examples 1-5 and Comparative Examples 1-5. After cleaning, the corrosion rate and deformation rate of the shield components were tested, and the results are shown in Table 1 below.

[0059] (1) Corrosion rate detection: The corrosion rate of the component is characterized by the component weight loss rate. The cleaned component is weighed, and the weight loss rate of the component is calculated based on the initial weight of the component. The formula for calculating the weight loss rate is: (initial weight - weight after cleaning) / initial weight.

[0060] (2) The deformation rate is detected by using the maximum inscribed circle method to detect the roundness of the bottom inner diameter of the part after cleaning, and the deformation rate of the part is calculated based on the initial roundness of the part. The formula for calculating the deformation rate of the part is: (initial roundness - roundness after cleaning) / initial roundness.

[0061] Table 1. Results of the cleaning effect evaluation of the cleaning methods provided in Examples 1-5 and Comparative Examples 1-5 According to the test results in Table 1, the cleaning methods provided in Examples 1-5 were effective in cleaning shield components with 800 μm thick Ti deposits on their surfaces. After cleaning, the surface of the components was clean and free of contaminants, with a weight loss rate of only 0.27-0.32% and a deformation rate of only 2.8-4.2%. In contrast, Comparative Example 1 used a 1:1 ratio of 66 v / v% nitric acid and 49 v / v% hydrofluoric acid as the leaching solution, and the resulting cleaning method left a small amount of contaminants on the surface of the shield components after cleaning. Comparative Example 2 used only 66 v / v% nitric acid as the leaching solution, and the resulting cleaning method caused slight corrosion on the surface of the shield components after cleaning, with a weight loss rate of 1.25%. Comparative Example 2 also used only 49 v / v% hydrofluoric acid as the leaching solution, and the resulting cleaning method left a small amount of contaminants on the surface of the shield components after cleaning. Comparative Example 4 controlled the gravity blasting pressure to 5 kg / cm². 2At that time, the weight loss rate of the obtained parts was as high as 1.44%, and the deformation rate of the parts was as high as 14.9%; Comparative Example 5 used 20% ammonia water and 40% hydrogen peroxide in a volume ratio of 1:4 as acid leaching solution and adopted the peeling sandblasting method. After cleaning, the surface of the parts was slightly corroded, and the weight loss rate was as high as 1.08%, and the deformation rate was as high as 81.7%.

[0062] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for cleaning shield components, characterized in that, Includes the following steps: Pre-protection, acid immersion, water immersion, gravity sandblasting, high-pressure water washing, ultrasonic cleaning, drying and packaging; In the pre-protection step, acid and alkali resistant tape is used to protect the bottom of the shield component, and a cover matching the shield component is used to press down 4 layers of PE bags, pressing them onto the inner edge of the cover; The acid leaching step uses an acid leaching solution of nitric acid and hydrofluoric acid in a volume ratio of (5-7):

1. The gravity sandblasting step involves sandblasting the surface of the shield component with alumina abrasive at a pressure of 3-4 kg / cm². 2 .

2. The cleaning method for shield components according to claim 1, characterized in that, The acid leaching time is 5-10 minutes.

3. The cleaning method for shield components according to claim 1, characterized in that, The concentration of nitric acid is 65-70 v / v, and the concentration of hydrofluoric acid is 48-50 v / v.

4. The cleaning method for shield components according to claim 1, characterized in that, In the high-pressure water washing step, the pressure of the high-pressure water gun is 120±10Psi, and the washing time is 2-4min.

5. The cleaning method for shield components according to claim 4, characterized in that, During the water washing process, the shield component is rotated once every 30 seconds, with each rotation being 90°.

6. The cleaning method for shield components according to claim 1, characterized in that, In the ultrasonic cleaning step, the ultrasonic frequency is 35-45kHz and the ultrasonic power density is 4-10W / in. 2 The ultrasonic cleaning time is 25-40 minutes.

7. The cleaning method for shield components according to claim 6, characterized in that, During the ultrasonic cleaning process, the shield component is rotated once every 10 minutes, with each rotation being 90°.

8. The cleaning method for shield components according to claim 1, characterized in that, The drying temperature is 130-160℃, and the time is 2-3 hours.

9. The cleaning method for shield components according to claim 1, characterized in that, After water immersion and ultrasonic cleaning, the shield components need to be purged with high-purity nitrogen gas at a pressure of 30±5 Psi.

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