TWI859149B - Method and apparatus for cleaning substrates - Google Patents

Abstract

The present invention provides a method for cleaning substrates comprising the steps of: placing a substrate on a substrate holder; implementing a bubble less or bubble-free pre-wetting process for the substrate; and implementing an ultra/mega sonic cleaning process for cleaning the substrate.

Description

Substrate cleaning method and cleaning device

The present invention relates to a method and apparatus for cleaning a substrate. More specifically, it relates to the application of acoustic energy in a pre-treatment process before cleaning a substrate to avoid destructive implosion of bubbles during the cleaning process of the substrate, thereby more effectively removing particles in the graphic structure on the substrate.

Semiconductor devices are manufactured on semiconductor substrates using many different processing steps to create transistors and interconnects. In recent years, transistors have evolved from two dimensions to three dimensions, such as finFET transistors and 3D NAND memory. In order to electrically connect the transistor terminals to the semiconductor substrate, conductive (such as metal) trenches, vias, etc. are formed in the dielectric material as part of the semiconductor device. Trenches and vias can transfer electrical signals and energy between transistors, internal circuits, and external circuits.

In order to form finFET transistors and interconnects on a semiconductor substrate, the semiconductor substrate needs to go through multiple steps, such as masking, etching, and deposition to form the desired electronic circuits. In particular, multiple masking and plasma etching steps can form patterns of finFETs, 3D NAND flash memory cells, and/or recessed areas in the dielectric layer of the semiconductor substrate as fins of transistors and/or trenches and vias of interconnects. Wet cleaning is required to remove particles and contaminants generated in the fin structure and/or trenches and vias during etching or photoresist ashing. In particular, as device manufacturing nodes extend to 16 or 14nm and below, sidewall loss of fins and/or trenches and vias is key to maintaining critical dimensions. To reduce or eliminate sidewall loss, it is important to use mild or diluted chemicals, sometimes only deionized water. However, diluted chemicals or deionized water are generally not effective in removing particles from fin structures, 3D NAND holes and/or trenches and vias. Therefore, in order to effectively remove these particles, mechanical forces such as ultrasound or megasonic waves are required. Ultrasonic waves or megasonic waves generate cavitation oscillations to provide mechanical forces to the substrate structure. Violent cavitation oscillations such as unstable cavitation oscillations or microjetting will damage these graphic structures. Maintaining stable or controlled cavitation oscillations is a key parameter to control the mechanical damage limit and effectively remove particles.

FIG. 1A and FIG. 1B illustrate that unstable cavitation oscillations damage the pattern structure 1030 on the substrate 1010 during the cleaning process of the substrate 1010. The unstable cavitation oscillations can be generated by the acoustic energy used to clean the substrate 1010. As shown in FIG. 1A and FIG. 1B, the micro-ejection caused by the implosion of the bubble 1050 occurs above the top of the pattern structure 1030 and is very violent (can reach thousands of atmospheres and thousands of degrees Celsius), which can destroy the pattern structure 1030 on the substrate 1010, especially when the feature size t is reduced to 70nm or less.

The damage to the substrate pattern structure caused by micro-ejection caused by bubble implosion is overcome by controlling the cavitation oscillation of the bubbles during the cleaning process. Stable or controllable cavitation oscillation can be achieved across the entire substrate to avoid pattern structure damage, which has been disclosed in patent application number PCT/CN2015/079342 filed on May 20, 2015.

In some cases, even if the power intensity of ultrasonic or megasonic waves used to clean the substrate is reduced to a very low level (almost no particle removal rate), damage to the pattern structure on the substrate still occurs. The amount of damage is small (less than 100). However, normally, the number of bubbles during ultrasonic or megasonic assisted cleaning is tens of thousands. The amount of damage to the pattern structure on the substrate does not match the number of bubbles. The mechanism of this phenomenon is not yet known.

As shown in FIG. 2A , during the process of ultrasonic or megasonic assisted cleaning of a substrate, there is a phenomenon that although the power intensity of the ultrasonic or megasonic wave used to clean the substrate 2010 is reduced to a very low level (almost no particle removal rate), damage to the graphic structure 2030 on the substrate 2010 still occurs. In addition, it is usually the single wall of the graphic structure 2030 that is damaged. FIG. 2A gives two examples. One example is that the single wall of the graphic structure 2030 is peeled off toward one side, and the other example is that a portion of the single wall of the graphic structure 2030 is removed. Although FIG. 2A only gives two examples, it should be recognized that other similar damages may occur. What causes these damages to occur?

2B to 2D , during the substrate cleaning process, small bubbles 2050 and 2052 tend to adhere to a solid surface, such as the surface of the substrate 2010 or the sidewall of the pattern structure 2030, as shown in FIGS. 2B and 2C . When the bubbles 2050 and 2052 are attached to the surface of the substrate 2010 or the sidewall of the pattern structure 2030, for example, the bubble 2052 is attached to the bottom corner of the pattern structure 2030, and the bubble 2050 is attached to a single sidewall of the pattern structure 2030, once these bubbles 2050 and 2052 implode, the pattern structure 2030 is peeled off from the sublayer on the substrate 2010 in the direction consistent with the direction of the bubble implosion force acting on the single sidewall, or a portion of the single sidewall of the pattern structure 2030 is removed, as shown in FIG. 2A . Although the intensity of the implosion is not as strong as that of the microjet, since the bubbles 2050 and 2052 are attached to the surface of the substrate 2010 and the side walls of the pattern structure 2030, the energy generated by the implosion of the small bubbles will also damage the pattern structure 2030.

Furthermore, during wet processing, small bubbles may merge into larger bubbles. Since bubbles tend to attach to solid surfaces, such as those of pattern structures and substrates, the merging of bubbles increases the risk of bubble implosion on the pattern structures, especially in critical geometries.

3A to 3H disclose the mechanism of the implosion of bubbles attached to the substrate and damage to the pattern structure on the substrate during the ultrasonic or megasonic assisted wet cleaning process according to the present invention. FIG3A illustrates that the cleaning liquid 3070 is delivered to the surface of the substrate 3010 having the pattern structure 3030, and at least one bubble 3050 is attached to the bottom corner of the pattern structure 3030. In the ultrasonic or megasonic positive pressure working process shown in FIG3B , F1 is the ultrasonic or megasonic pressure acting on the bubble 3050, F2 is the reaction force on the bubble 3050 generated by the substrate 3010 when the bubble 3050 is pressed on the substrate 3010, and F3 is the reaction force on the bubble 3050 generated by the side wall of the graphic structure 3030 when the bubble 3050 is pressed on the side wall of the graphic structure 3030. In the ultrasonic or megasonic negative pressure working process shown in FIG3C and FIG3D , the bubble 3050 expands due to the ultrasonic or megasonic negative force stretching the bubble 3050. During the expansion of the bubble volume, F1' is the force of the bubble 3050 pushing the cleaning liquid 3070, F2' is the force of the bubble 3050 pushing the substrate 3010, and F3' is the force of the bubble 3050 pushing the side wall of the graphic structure 3030. After several cycles of alternating positive and negative sound pressures of ultrasonic or megasonic waves, the gas temperature in the bubble becomes higher and higher, the bubble volume becomes larger and larger, and finally the bubble implodes 3051, which generates an implosion force F1'' acting on the cleaning liquid 3070, a force F2'' acting on the substrate 3010, and a force F3'' acting on the side wall of the graphic structure 3030, as shown in FIG3G. The implosion force causes the side wall of the graphic structure 3030 to be damaged, as shown in FIG3H.

In order to avoid damage to the pattern structure on the substrate due to bubble implosion during ultrasonic or megasonic assisted wet cleaning, it is best to separate the bubbles from the surface of the pattern structure and the surface of the substrate before applying acoustic energy to the cleaning liquid to clean the substrate, as disclosed in the patent application number PCT/CN2018/073723 filed on January 23, 2018. However, it is difficult to separate all the bubbles from the surface of the pattern structure. Therefore, the remaining bubbles on the surface of the pattern structure may still cause damage to the pattern structure on the substrate.

Therefore, the purpose of the present invention is to provide a substrate cleaning method and a cleaning device.

According to an embodiment of the present invention, a substrate cleaning method is proposed, comprising the following steps: placing a substrate on a substrate holding device; performing a pre-wetting process with little or no bubbles on the substrate; and performing an ultrasonic or megasonic cleaning process to clean the substrate.

According to an embodiment of the present invention, a substrate cleaning device is provided, comprising: a first chamber, configured to be connected to a pump to form a vacuum environment in the first chamber; a substrate holding device, configured to be arranged in the first chamber to hold the substrate; at least one nozzle, configured to provide a pre-wetting chemical liquid or chemical mist to the surface of the substrate to form a chemical liquid layer with few bubbles or no bubbles on the substrate; and a second chamber, configured with an ultrasonic or megasonic device to clean the substrate.

According to another embodiment of the present invention, a substrate cleaning device is provided, comprising: a chamber, configured to be connected to a pump to form a vacuum environment in the chamber; a substrate holding device, configured to be arranged in the chamber to hold the substrate; at least one nozzle, configured to provide a pre-wetting chemical liquid or chemical mist to the surface of the substrate after the vacuum environment is formed in the chamber to form a chemical liquid layer with few or no bubbles on the substrate; and an ultrasonic or megasonic device, configured to clean the substrate.

According to another embodiment of the present invention, a substrate cleaning device is provided, comprising: a first chamber, configured to be connected to a vaporization unit, the vaporization unit being configured to convert a pre-wetting chemical solution into a gaseous state; a substrate holding device, configured to be arranged in the first chamber to hold the substrate; at least one nozzle, configured to be connected to the vaporization unit to provide vaporized liquid molecules to the surface of the substrate to form a pre-wetting chemical liquid layer with few or no bubbles on the substrate; and a second chamber, configured with an ultrasonic or megasonic device to clean the substrate.

According to another embodiment of the present invention, a substrate cleaning device is provided, comprising: a chamber; a vaporization unit configured to convert a pre-wetting chemical solution into a gaseous state; a substrate holding device configured to be arranged in the chamber to hold the substrate; at least one nozzle configured to be connected to the vaporization unit to provide vaporized liquid molecules to the surface of the substrate to form a pre-wetting chemical liquid layer with few or no bubbles on the substrate; at least one nozzle configured to provide a cleaning chemical liquid or chemical mist to the surface of the substrate to clean the substrate; and an ultrasonic or megasonic device configured to clean the substrate.

In summary, the present invention implements a pre-wetting process with few or no bubbles on the substrate before implementing an ultrasonic or megasonic cleaning process to clean the substrate. When the ultrasonic or megasonic cleaning process is implemented, the bubble implosion is effectively prevented from causing damage to the graphic structure on the substrate. By pre-treating the substrate, the bubbles no longer tend to adhere to the surface of the graphic structure, or the bubbles near the surface of the graphic structure will be easily removed before they adhere to the surface of the graphic structure. In this way, the bubble implosion can be better controlled by ultrasonic or megasonic power control without being affected by the accumulation or attachment of bubbles on the surface of the graphic structure, especially without being affected by critical geometric parts.

1010‧‧‧Substrate

1030‧‧‧Pattern structure

1050‧‧‧Bubbles

2010‧‧‧Substrate

2030‧‧‧Pattern structure

2050‧‧‧Bubbles

2052‧‧‧Bubbles

3010‧‧‧Substrate

3030‧‧‧Pattern structure

3050‧‧‧Bubbles

3051‧‧‧Bubble implosion

3070‧‧‧Cleaning fluid

4000‧‧‧Cleaning chamber

4001‧‧‧Cleaning the cup cover

4002‧‧‧Substrate holder

4003‧‧‧Rotary actuator

4005‧‧‧Swinging arms

4006‧‧‧Ultrasonic or megasonic devices

4008‧‧‧Nozzle arm

4009‧‧‧Spray nozzle

4010‧‧‧Substrate

4017‧‧‧Exhaust port

4020‧‧‧Pre-wetting chamber

4021‧‧‧Substrate holder

4022‧‧‧Vacuum port

4023‧‧‧Spray head

4024‧‧‧Rotary drive device

4070‧‧‧Cleaning fluid

5000‧‧‧Cleaning chamber

5001‧‧‧Cleaning cup cover

5002‧‧‧Substrate holder

5003‧‧‧Rotary actuator

5005‧‧‧Swinging arms

5006‧‧‧Ultrasonic or megasonic devices

5008‧‧‧Nozzle arm

5009‧‧‧Spray nozzle

5010‧‧‧Substrate

5015‧‧‧Fan filter unit

5017‧‧‧Exhaust port

5018‧‧‧Vacuum port

5045‧‧‧Second stopper

5047‧‧‧First blocker

6000‧‧‧Cleaning chamber

6001‧‧‧Cleaning cup cover

6002‧‧‧Substrate holder

6003‧‧‧Rotary actuator

6005‧‧‧Swinging arms

6006‧‧‧Ultrasonic or megasonic devices

6008‧‧‧Nozzle arm

6009‧‧‧Nozzle

6010‧‧‧Substrate

6015‧‧‧Fan filter unit

6017‧‧‧Exhaust port

6020‧‧‧Pre-wetting chamber

6021‧‧‧Substrate holder

6023‧‧‧Spray head

6024‧‧‧Rotary drive device

6030‧‧‧Gasification unit

6031‧‧‧Chemical solution

7000‧‧‧Cleaning chamber

7001‧‧‧Cleaning cup cover

7002‧‧‧Substrate holder

7003‧‧‧Rotary actuator

7005‧‧‧Swinging arms

7006‧‧‧Ultrasonic or megasonic devices

7008‧‧‧Nozzle arm

7009‧‧‧Spray nozzle

7010‧‧‧Substrate

7015‧‧‧Fan filter unit

7017‧‧‧Exhaust port

7030‧‧‧Gasification unit

7031‧‧‧Chemical solution

7070‧‧‧Cleaning fluid

8010‧‧‧Substrate

8020‧‧‧Thin layer

9010‧‧‧Substrate

9060‧‧‧Graphic structure

9061‧‧‧Burrs

9062‧‧‧Bubbles

F1‧‧‧Ultrasonic or megasonic pressure acting on bubbles

F1’‧‧‧The force of bubbles pushing the cleaning fluid

F1"‧‧‧Produces an implosion force acting on the cleaning fluid

F2‧‧‧When the air bubble is pressed on the substrate, the reaction force generated by the substrate on the air bubble

F2’‧‧‧The force of the bubble pushing the substrate

F2”‧‧‧Force acting on the substrate

F3‧‧‧When the air bubble presses on the side wall of the graphic structure, the reaction force generated by the side wall of the graphic structure acts on the air bubble

F3’‧‧‧The force of the bubble pushing the side wall of the pattern structure

F3”‧‧‧Force acting on the side wall of the pattern structure

Figures 1A to 1B illustrate schematic diagrams of pattern structures on a substrate damaged by unstable cavitation oscillation during the cleaning process.

Figures 2A to 2D illustrate schematic diagrams of a pattern structure attached to a substrate and damaged by a bubble implosion.

Figures 3A to 3H illustrate the mechanism of bubble implosion damaging the surface of the graphic structure attached to the substrate.

4A to 4B illustrate schematic diagrams of an apparatus for cleaning a substrate according to an embodiment of the present invention.

FIG5 depicts a schematic diagram of an apparatus for cleaning a substrate according to another embodiment of the present invention.

Figures 6A to 6B illustrate schematic diagrams of an apparatus for cleaning a substrate according to another embodiment of the present invention.

FIG7 depicts a schematic diagram of a device for cleaning a substrate according to another embodiment of the present invention.

8A to 8B illustrate schematic diagrams of a substrate cleaning method according to an embodiment of the present invention.

Figures 9A to 9D illustrate schematic diagrams of a substrate cleaning method according to another embodiment of the present invention.

Referring to FIGS. 4A to 4B , a substrate cleaning device according to an embodiment of the present invention is disclosed. The device can pre-treat a substrate before a subsequent ultrasonic or megasonic cleaning process to obtain a substrate surface with few or no bubbles. The device includes a pre-wetting chamber 4020 and a cleaning chamber 4000. A substrate 4010 is pre-treated in the pre-wetting chamber 4020 to obtain a pre-wetting surface with few or no bubbles, and then the substrate 4010 is transferred to the cleaning chamber 4000 for a subsequent ultrasonic or megasonic cleaning process. FIG. 4A discloses the pre-wetting chamber 4020. The pre-wetting chamber 4020 includes a door for moving the substrate into or out of the pre-wetting chamber 4020, a vacuum port 4022 connected to a vacuum pump to generate a vacuum environment in the pre-wetting chamber 4020, a substrate holder 4021 for holding the substrate 4010 in the pre-wetting chamber 4020, a rotation drive device 4024 for driving the substrate 4010 to rotate, and at least one nozzle 4023 located above the substrate 4010 for providing a pre-wetting chemical liquid or chemical mist to the surface of the substrate 4010 to form a chemical liquid layer with few or no bubbles on the substrate 4010. In one embodiment, a plurality of nozzles 4023 are used to evenly distribute the pre-wetting chemical liquid on the surface of the substrate 4010. The vacuum level in the pre-wetting chamber 4020 is set at 25 Torr or above. FIG4B shows the cleaning chamber 4000. The cleaning chamber 4000 includes a substrate support 4002 for holding a substrate 4010, a cleaning cup 4001 arranged around the substrate support 4002 to prevent the cleaning liquid 4070 from splashing, a rotary actuator 4003 connected to the substrate support 4002 to drive the substrate support 4002 to rotate, a fan filter unit 4015 (FFU) arranged at the top of the cleaning chamber 4000, at least one exhaust port 4017, a swing arm 4005 equipped with an ultrasonic or megasonic device 4006 to transmit acoustic energy to the cleaning liquid 4070 to clean the substrate 4010, and multiple nozzle arms 4008, each nozzle arm 4008 is equipped with at least one nozzle 4009 to provide chemical liquid, chemical mist or dry gas to the surface of the substrate 4010.

According to an embodiment of the present invention, a substrate cleaning method is proposed, comprising the following steps:

Step 1: Transfer the substrate 4010 into the pre-wetting chamber 4020, and the substrate 4010 is held by the substrate holder 4021.

Step 2: Close the door of the pre-wetting chamber 4020 and start evacuating the pre-wetting chamber 4020 through the vacuum port 4022 to establish a vacuum environment in the pre-wetting chamber 4020 at a set time. The vacuum degree in the pre-wetting chamber 4020 is set at 25 Torr or above.

Step 3: After the vacuum environment is formed, the substrate 4010 is rotated at a speed of 100-200 RPM, and a pre-wetting chemical solution or chemical mist is provided to the surface of the substrate 4010.

Step 4: Rotate the substrate 4010 at a speed of 400-600 RPM, then stop the rotation of the substrate 4010 and release the vacuum pressure in the pre-wetting chamber 4020, and then open the door of the pre-wetting chamber 4020.

Step 5: Transfer the substrate 4010 from the pre-wetting chamber 4020 to the cleaning chamber 4000, and the substrate 4010 is held by the substrate holder 4002 in the cleaning chamber 4000.

Step 6: Drive the substrate 4010 to rotate at a set low speed of 10RPM to 1000RPM.

Step 7: Swing the nozzle arm 4008 to a position above the surface of the substrate 4010 to provide a cleaning solution to the surface of the substrate 4010. A variety of chemical solutions can be used in this step.

Step 8: Provide a cleaning liquid to the surface of the substrate 4010 for use in an ultrasonic or megasonic cleaning process.

Step 9: Move the ultrasonic or megasonic device 4006 downward to a certain height from the surface of the substrate 4010, and fill the gap between the ultrasonic or megasonic device 4006 and the surface of the substrate 4010 with cleaning liquid as a medium for transmitting sound waves.

Step 10: Turn on the ultrasonic or megasonic device 4006 and clean the surface of the substrate 4010 according to the programmed recipe within a certain period of time.

Step 11: Turn off the ultrasonic or megasonic device 4006 and move the ultrasonic or megasonic device 4006 upward.

Step 12: Provide a rinse chemical solution or deionized water to the surface of substrate 4010 to clean substrate 4010.

Step 13: Dry the substrate 4010.

Step 14: Stop rotating the substrate 4010 and remove the substrate 4010 from the cleaning chamber 4000.

The purpose of step 2 to step 3 is a pre-wetting process with few or no bubbles. Since the gas such as air or nitrogen in the pre-wetting chamber 4020 is evacuated in step 2, a vacuum environment is established around the surface of the substrate 4010. Therefore, in step 3, the pre-wetting chemical solution enters the through holes and grooves on the substrate 4010 without being blocked by bubbles.

Steps 7 to 11 can be repeated for at least one cycle. At least one chemical solution, such as SC1 (a mixture of ammonium hydroxide, hydrogen peroxide and water), ozone water, ammonia water, etc. can be used in this cleaning cycle.

In the cleaning steps from step 6 to step 12, the rotation speed of the substrate 4010 can be set at 10RPM to 1500RPM according to different time periods and controlled by a programmable recipe.

FIG. 5 discloses a substrate cleaning device according to another embodiment of the present invention. The device can pre-treat a substrate before a subsequent ultrasonic or megasonic cleaning process to obtain a substrate surface with few or no bubbles. The device combines the pre-wetting function with the cleaning function in a cleaning chamber 5000, wherein the substrate is pre-treated to obtain a pre-wetted surface with few or no bubbles, and then cleaned by a subsequent ultrasonic or megasonic cleaning process. FIG. 5 discloses a cleaning chamber 5000. The cleaning chamber 5000 includes a cleaning cup 5001, a vacuum port 5018 connected to a vacuum pump to generate a vacuum environment in the cleaning chamber 5000, a rotary actuator 5003, a substrate support 5002, a fan filter unit 5015 for generating a downward air flow, at least one exhaust port 5017, a first blocker 5047 for the exhaust port 5017, and a fan filter unit 5015 for generating a downward air flow. The second baffle 5045 of the fan filter unit 5015, the swing arm 5005 equipped with the ultrasonic or megasonic device 5006, and multiple nozzle arms 5008, each nozzle arm 5008 is equipped with at least one nozzle 5009 to provide pre-wetting chemical liquid or chemical mist, cleaning chemical liquid or chemical mist or dry gas to the surface of the substrate 5010. When the vacuum port 5018 starts to form a vacuum pressure in the cleaning chamber 5000 during the pre-treatment process, the fan filter unit 5015 and the exhaust port 5017 stop generating downward airflow on the surface of the substrate 5010. The second baffle 5045 is closed to isolate the fan filter unit 5015 and the cleaning chamber 5000, and the first baffle 5047 is closed to isolate the exhaust port 5017 and the cleaning chamber 5000, thereby establishing a vacuum environment in the cleaning chamber 5000. In the subsequent cleaning process, the fan filter unit 5015 and the exhaust port 5017 are opened to generate a downward airflow.

According to another embodiment of the present invention, a substrate cleaning method is proposed, comprising the following steps:

Step 1: Transfer the substrate 5010 into the cleaning chamber 5000, and the substrate 5010 is held by the substrate holder 5002.

Step 2: Close the door of the cleaning chamber 5000, close the fan filter unit 5015 and the exhaust port 5017, close the first baffle 5047 and the second baffle 5045, and start evacuating the cleaning chamber 5000 through the vacuum port 5018 to establish a vacuum environment in the cleaning chamber 5000 at a set time. The vacuum degree in the cleaning chamber 5000 is set at 25 Torr or above.

Step 3: After the vacuum environment is formed, drive the substrate 5010 to rotate at a set low speed of 10RPM to 1000RPM.

Step 4: Rotate the pre-wetting spray head to a position above the surface of the substrate 5010 to provide pre-wetting chemical liquid or chemical mist to the surface of the substrate 5010.

Step 5: Release the vacuum pressure in the cleaning chamber 5000, open the fan filter unit 5015, the exhaust port 5017, the first baffle 5047 and the second baffle 5045 to form a downward airflow on the substrate 5010.

Step 6: Swing the nozzle arm to a position above the surface of the substrate 5010 to provide a cleaning solution to the surface of the substrate 5010. A variety of chemical solutions can be used in this step.

Step 7: Provide a cleaning liquid to the surface of the substrate 5010 for use in an ultrasonic or megasonic cleaning process.

Step 8: Move the ultrasonic or megasonic device 5006 downward to a certain height from the surface of the substrate 5010, and fill the gap between the ultrasonic or megasonic device 5006 and the surface of the substrate 5010 with cleaning liquid as a medium for transmitting sound waves.

Step 9: Turn on the ultrasonic or megasonic device 5006 and clean the surface of the substrate 5010 according to the programmed recipe within a certain period of time.

Step 10: Turn off the ultrasonic or megasonic device 5006 and move the ultrasonic or megasonic device 5006 upward.

Step 11: Provide a rinse chemical solution or deionized water to the surface of the substrate 5010 to clean the substrate 5010.

Step 12: Dry the substrate 5010.

Step 13: Stop rotating the substrate 5010 and remove the substrate 5010 from the cleaning chamber 5000.

The purpose of step 2 to step 4 is a pre-wetting process with few or no bubbles. Since the gas such as air or nitrogen in the cleaning chamber 5000 is evacuated in step 2, a vacuum environment is established around the surface of the substrate 5010. Therefore, in step 4, the pre-wetting chemical solution enters the through holes and grooves on the substrate 5010 without being blocked by bubbles.

Steps 6 to 10 can be repeated for at least one cycle. At least one chemical solution, such as SC1 (a mixture of ammonium hydroxide, hydrogen peroxide and water), ozone water, ammonia water, etc. can be used in this cleaning cycle.

In the cleaning steps from step 5 to step 11, the rotation speed of the substrate 5010 can be set at 10RPM to 1500RPM according to different time periods and controlled by a programmable recipe.

6A to 6B disclose a substrate cleaning device according to another embodiment of the present invention. The device can pre-treat a substrate before a subsequent ultrasonic or megasonic cleaning process to obtain a substrate surface with few or no bubbles. The device includes a pre-wetting chamber 6020 and a cleaning chamber 6000. The substrate is pre-treated in the pre-wetting chamber 6020 to obtain a pre-wetting surface with few or no bubbles, and then the substrate is transferred to the cleaning chamber 6000 for a subsequent ultrasonic or megasonic cleaning process. FIG. 6A discloses the pre-wetting chamber 6020. The pre-wetting chamber 6020 includes: a vaporization unit 6030, which is configured to convert a pre-wetting liquid chemical solution 6031 into gas phase molecules; a rotation drive device 6024, which is configured to drive the substrate 6010 to rotate; at least one nozzle 6023, which is configured to be connected to the vaporization unit 6030 and provide vaporized liquid molecules to the surface of the substrate 6010 to form a pre-wetting chemical liquid layer with few or no bubbles on the substrate 6010; and a substrate holder 6021, which is configured to hold the substrate 6010 in the pre-wetting chamber 6020. In one embodiment, a plurality of nozzles 6023 are used to evenly distribute the vaporized liquid molecules on the surface of the substrate 6010. The vaporization unit 6030 is used to convert the pre-wetting chemical solution 6031 in the liquid phase into gas phase molecules. In one embodiment, the vaporization unit 6030 converts the pre-wetting chemical solution 6031 into gas phase molecules by using a sonication method. When the chemical liquid vapor is formed by using the sonication method, the chemical liquid vapor is heated to a temperature higher than the temperature of the substrate 6010. Alternatively, the substrate 6010 is cooled to a temperature lower than the temperature of the chemical liquid vapor. In another embodiment, the vaporization unit 6030 converts the pre-wetting chemical solution 6031 into gas phase molecules by heating. The vaporized liquid molecules can also be carried by a medium gas such as nitrogen, air, ozone, ammonia, hydrogen or helium. The carrier gas can be an inert gas that is only used to carry the vaporized liquid molecules, or it can be an active gas that assists the vaporized liquid molecules in oxidation or passivation of the substrate surface.

The vaporized liquid molecules are more easily transported from the large amount of vapor environment to the pattern structures such as the grooves and through holes on the substrate 6010. After the vaporized liquid molecules are distributed on the surface of the substrate 8010, the vaporized liquid molecules condense on the surface of the substrate 8010 to form a thin layer 8020 of pre-wetting liquid molecules, and the liquid molecules are formed layer by layer from bottom to top in the through holes and grooves of the substrate 8010, as shown in Figures 8A to 8B. However, if part of the surface of the substrate is not well wetted, this bottom-to-top liquid layer formation will be affected, and due to surface tension, the liquid layer will be broken at the place on the substrate surface that is not well wetted. In one embodiment, the vaporization unit 6030 converts the pre-wetting chemical solution of the liquid phase containing the surfactant or additive into vaporized mixed liquid molecules containing the surfactant or additive molecules. The vaporized mixed liquid molecules containing the surfactant or additive molecules can increase the wettability of the liquid chemical solution on the substrate surface, so that the liquid chemical solution can fill the through holes, grooves and other graphic structures on the substrate 6010 from bottom to top without bubble clogging. Carboxyl-containing ethylenediaminetetraacetic acid (EDTA), tetracarboxyl ethylenediaminetetrapropionic acid (EDTP) acid or salt, etc. are doped in the liquid chemical solution as a surfactant to improve the wettability of the chemical solution. In another embodiment, the vaporization unit 6030 converts a pre-wetting chemical solution containing a liquid phase of a chemical for oxidizing the surface of the substrate 6010 from hydrophobic to hydrophilic into vaporized mixed liquid molecules. The vaporized mixed liquid molecules can increase the wettability of the liquid chemical solution on the substrate surface, so that the liquid chemical solution can fill the through holes, grooves and other graphic structures on the substrate 6010 from bottom to top without bubble clogging. Chemicals such as ozone solution or SC1 solution (a mixture of ammonium hydroxide, hydrogen peroxide and water) are used to oxidize a hydrophobic surface material such as a silicon or polycrystalline silicon layer into a hydrophilic silicon oxide layer.

FIG6B discloses a cleaning chamber 6000. The cleaning chamber 6000 includes: a cleaning cup cover 6001, a rotary actuator 6003, a substrate support 6002, a fan filter unit 6015, at least one exhaust port 6017, a swing arm 6005 equipped with an ultrasonic or megasonic device 6006, and multiple nozzle arms 6008, each nozzle arm 6008 is equipped with at least one nozzle 6009 to provide a cleaning chemical liquid or chemical mist or dry gas to the surface of the substrate 6010.

According to an embodiment of the present invention, a substrate cleaning method is proposed, comprising the following steps:

Step 1: Transfer the substrate 6010 into the pre-wetting chamber 6020, and the substrate 6010 is held by the substrate holder 6021.

Step 2: Supply the pre-wetting chemical solution to the vaporization unit 6030 to generate vaporized liquid molecules.

Step 3: Close the door of the pre-wetting chamber 6020, drive the substrate 6010 to rotate, and provide vaporized liquid molecules to the surface of the substrate 6010 through the nozzle 6023 to perform the pre-wetting process.

Step 4: Transfer the substrate 6010 from the pre-wetting chamber 6020 to the cleaning chamber 6000, and the substrate 6010 is held by the substrate holder 6002 in the cleaning chamber 6000.

Step 5: Drive the substrate 6010 to rotate at a set low speed of 10RPM to 1000RPM.

Step 6: Swing the nozzle arm 6008 to a position above the surface of the substrate 6010 to provide a cleaning solution to the surface of the substrate 6010. A variety of chemical solutions can be used in this step.

Step 7: Provide a cleaning liquid to the surface of the substrate 6010 for use in an ultrasonic or megasonic cleaning process.

Step 8: Move the ultrasonic or megasonic device 6006 downward to a certain height from the surface of the substrate 6010, and fill the gap between the ultrasonic or megasonic device 6006 and the surface of the substrate 6010 with cleaning liquid as a medium for transmitting sound waves.

Step 9: Turn on the ultrasonic or megasonic device 6006 and clean the surface of the substrate 6010 according to the programmed recipe within a certain period of time.

Step 10: Turn off the ultrasonic or megasonic device 6006 and move the ultrasonic or megasonic device 6006 upward.

Step 11: Provide a rinse chemical solution or deionized water to the surface of the substrate 6010 to clean the substrate 6010.

Step 12: Dry the substrate 6010.

Step 13: Stop rotating the substrate 6010 and remove the substrate 6010 from the cleaning chamber 6000.

The purpose of step 2 to step 3 is a pre-wetting process with few or no bubbles. The vaporized liquid molecules are distributed on the surface of the substrate 6010, and the vaporized liquid molecules condense on the surface of the substrate 6010 to form a thin layer of pre-wetting liquid molecules. The liquid molecules are formed layer by layer from bottom to top in the through holes and grooves of the substrate 6010.

Steps 7 to 10 can be repeated for at least one cycle. At least one chemical solution, such as SC1 (a mixture of ammonium hydroxide, hydrogen peroxide and water), ozone water, ammonia water, etc. can be used in this cleaning cycle.

In the cleaning steps from step 6 to step 11, the rotation speed of the substrate 6010 can be set at 10RPM to 1500RPM according to different time periods and controlled by a programmable recipe.

FIG. 7 discloses a substrate cleaning device according to an embodiment of the present invention. The device can pre-treat a substrate before a subsequent ultrasonic or megasonic cleaning process to obtain a substrate surface with few or no bubbles. The device combines a pre-wetting function with a cleaning function in a cleaning chamber 7000, wherein the substrate is pre-treated to obtain a pre-wetting surface with few or no bubbles, and then cleaned by a subsequent ultrasonic or megasonic cleaning process. FIG. 7 discloses a cleaning chamber 7000. The cleaning chamber 7000 includes: a cleaning cup cover 7001, a rotary actuator 7003, a substrate support 7002, a fan filter unit 7015, at least one exhaust port 7017, a swing arm 7005 equipped with an ultrasonic or megasonic device 7006, a gasification unit 7030 for converting a pre-wetted liquid chemical solution 7031 into gas phase molecules, and a plurality of nozzle arms 7008, each of which has a nozzle. The arm 7008 is equipped with at least one nozzle 7023 and at least one nozzle 7009. The nozzle 7023 is connected to the vaporization unit 7030 to provide vaporized liquid molecules to the surface of the substrate 7010 to form a pre-wetting chemical liquid layer with few bubbles or no bubbles on the substrate 7010. The nozzle 7009 is used to provide a chemical liquid or chemical mist and a dry gas for cleaning to the surface of the substrate 7010. In one embodiment, a plurality of nozzles 7023 are used to evenly distribute the vaporized liquid molecules on the surface of the substrate 7010. The vaporization unit 7030 is used to convert the pre-wetting chemical solution 7031 in the liquid phase into gas phase molecules. In one embodiment, the vaporization unit 7030 converts the pre-wetted chemical solution 7031 into gas phase molecules by ultrasonic generation. In another embodiment, the vaporization unit 7030 converts the pre-wetted chemical solution 7031 into gas phase molecules by heating. The vaporized liquid molecules can also be carried by a medium gas such as nitrogen, air, ozone, ammonia, hydrogen or helium. The carrier gas can be an inert gas that is only used to carry the vaporized liquid molecules, or it can be an active gas to assist the vaporized liquid molecules in oxidation or passivation of the substrate 7010 surface.

The vaporized liquid molecules are more easily transported from the large amount of vapor environment to the pattern structures such as the grooves and through holes on the substrate 7010. After the vaporized liquid molecules are distributed on the surface of the substrate 7010, the vaporized liquid molecules condense on the surface of the substrate 7010 to form a thin layer 8020 of pre-wetting liquid molecules, and the liquid molecules are formed layer by layer from bottom to top in the through holes and grooves of the substrate 7010, as shown in Figures 8A to 8B. However, if part of the surface of the substrate 7010 is not well wetted, this bottom-to-top liquid layer formation will be affected, and due to surface tension, the liquid layer will be broken at the place on the substrate surface that is not well wetted. In one embodiment, the vaporization unit 7030 converts the pre-wetting chemical solution of the liquid phase containing the surfactant or additive into vaporized mixed liquid molecules containing the surfactant or additive molecules. The vaporized mixed liquid molecules containing the surfactant or additive molecules can increase the wettability of the liquid chemical solution on the substrate surface, so that the liquid chemical solution can fill the through holes, grooves and other graphic structures on the substrate 7010 from bottom to top without bubble clogging. Carboxyl-containing ethylenediaminetetraacetic acid (EDTA), tetracarboxyl ethylenediaminetetrapropionic acid (EDTP) acid or salt, etc., are doped into the liquid chemical solution as a surfactant to improve the wettability of the chemical solution. In another embodiment, the vaporization unit 7030 converts a pre-wetting chemical solution containing a liquid phase of a chemical for oxidizing the surface of the substrate 7010 from hydrophobic to hydrophilic into vaporized mixed liquid molecules. The vaporized mixed liquid molecules can increase the wettability of the liquid chemical solution on the substrate surface, so that the liquid chemical solution can fill the through holes, grooves and other graphic structures on the substrate 7010 from bottom to top without bubble clogging. Chemicals such as ozone solution or SC1 solution (a mixture of ammonium hydroxide, hydrogen peroxide, and water) are used to oxidize a hydrophobic surface material such as a silicon or polysilicon layer into a hydrophilic silicon oxide layer.

According to another embodiment of the present invention, a substrate cleaning method is proposed, comprising the following steps:

Step 1: Transfer the substrate 7010 into the cleaning chamber 7000, and the substrate 7010 is held by the substrate holder 7002.

Step 2: Drive the substrate 7010 to rotate at a set low speed of 10RPM to 1000RPM.

Step 3: Supply the pre-wetting chemical solution to the vaporization unit 7030 to generate vaporized liquid molecules.

Step 4: Swing the nozzle arm 7008 to a position above the surface of the substrate 7010, and provide vaporized liquid molecules to the surface of the substrate 7010 through the nozzle 7023 to perform a pre-wetting process.

Step 5: Use nozzle 7009 to provide cleaning solution to the surface of substrate 7010. A variety of chemical solutions can be used in this step.

Step 6: Provide a cleaning liquid to the surface of the substrate 7010 for use in an ultrasonic or megasonic cleaning process.

Step 7: Move the ultrasonic or megasonic device 7006 downward to a certain height from the surface of the substrate 7010, and fill the gap between the ultrasonic or megasonic device 7006 and the surface of the substrate 7010 with a cleaning liquid 7070 as a medium for transmitting sound waves.

Step 8: Turn on the ultrasonic or megasonic device 7006 and clean the surface of the substrate 7010 according to the programmed recipe within a certain period of time.

Step 9: Turn off the ultrasonic or megasonic device 7006 and move the ultrasonic or megasonic device 7006 upward.

Step 10: Provide a rinse chemical solution or deionized water to the surface of the substrate 7010 to clean the substrate 7010.

Step 11: Dry the substrate 7010.

Step 12: Stop rotating the substrate 7010 and remove the substrate 7010 from the cleaning chamber 7000.

The purpose of step 2 to step 4 is a pre-wetting process with few or no bubbles. The vaporized liquid molecules are distributed on the surface of the substrate 7010, and the vaporized liquid molecules condense on the surface of the substrate 7010 to form a thin layer of pre-wetting liquid molecules. The liquid molecules are formed layer by layer from bottom to top in the through holes and grooves of the substrate 7010.

Steps 6 to 9 can be repeated for at least one cycle. At least one chemical solution, such as SC1 (a mixture of ammonium hydroxide, hydrogen peroxide and water), ozone water, ammonia water, etc. can be used in this cleaning cycle.

In the cleaning steps from step 5 to step 10, the rotation speed of the substrate 7010 can be set at 10RPM to 1500RPM according to different time periods and controlled by a programmable recipe.

9A to 9B illustrate a substrate 9010 having a pattern structure 9060, and there are some scum or burrs 9061 in the recessed area of the substrate 9010. During the pre-wetting process and the subsequent cleaning process, bubbles 9062 will accumulate around these areas with scum or burrs 9061, which will cause the pattern structure 9060 to be damaged as shown in FIG2A during the ultrasonic or megasonic cleaning process. Therefore, it is preferred that the scum and burrs 9061 are removed using a pre-treatment unit before performing a pre-wetting process with less or no bubbles to obtain a smooth surface of the pattern structure 9060, as shown in FIG9C. In this case, no bubbles will adhere to the scum or burr surface during the pre-wetting process, as shown in FIG. 9D. In one embodiment, high energy plasma is used to remove scum and burr 9061 on the pattern structure 9060 to obtain a smooth surface of the pattern structure. Then, the substrate 9010 is transferred to the pre-wetting chamber to perform a pre-wetting process with few or no bubbles, and to the cleaning chamber to perform an ultrasonic or megasonic cleaning process.

In summary, the present invention has specifically and detailedly disclosed the relevant technology through the above-mentioned implementation methods and related diagrams, so that technical personnel in this field can implement it accordingly. The above-mentioned embodiments are only used to illustrate the present invention, not to limit the present invention. The scope of rights of the present invention should be defined by the scope of the patent application of the present invention. As for the change of the number of components described in this article or the replacement of equivalent components, etc., they should still fall within the scope of rights of the present invention.

4010‧‧‧Substrate

4020‧‧‧Pre-wetting chamber

4021‧‧‧Substrate holder

4022‧‧‧Vacuum port

4023‧‧‧Spray head

4024‧‧‧Rotary drive device

Claims (18)

A substrate cleaning method includes: placing a substrate on a substrate holding device; performing a pre-wetting process with few bubbles or no bubbles on the substrate, wherein the pre-wetting process with few bubbles or no bubbles includes: vaporizing a pre-wetting chemical solution, and then providing vaporized liquid molecules to the substrate surface to form a pre-wetting chemical liquid layer on the substrate; performing an ultrasonic or megasonic cleaning process to clean the substrate; and before performing the pre-wetting process with few bubbles or no bubbles on the substrate, removing scum or burrs to improve the surface smoothness of the recessed area of the substrate, and the scum and burrs absorb bubbles. A method as claimed in claim 1, wherein the pre-wetted chemical solution is converted into gas phase molecules using sonication. The method as described in claim 2 further includes heating the vaporized liquid molecules so that the temperature of the vaporized liquid molecules is higher than the temperature of the substrate. The method as described in claim 2 further includes cooling the substrate so that the temperature of the substrate is lower than the temperature of the vaporized liquid molecules. A method as claimed in claim 1, wherein the pre-wetted chemical solution is converted into gas phase molecules by heating. A method as described in claim 1, wherein the pre-wetting chemical solution includes a surfactant or an additive. The method as claimed in claim 6, wherein the surfactant is a carboxyl-containing ethylenediaminetetraacetic acid (EDTA) or tetracarboxyl ethylenediaminetetrapropionic acid (EDTP) acid or salt. A method as claimed in claim 1, wherein the pre-wetting chemical solution includes an oxidant to oxidize the surface of the substrate from hydrophobic to hydrophilic. The method as described in claim 8, wherein the oxidant is an ozone solution or an SC1 solution. A substrate cleaning device comprises: a first chamber, configured to be connected to a pump to form a vacuum environment in the first chamber; a substrate holding device, configured to be arranged in the first chamber to hold a substrate; at least one nozzle, configured to provide a pre-wetting chemical liquid or chemical mist to the surface of the substrate to form a chemical liquid layer with few bubbles or no bubbles on the substrate; a second chamber, configured with an ultrasonic or megasonic device to clean the substrate; and a pre-treatment unit, configured to provide a pre-wetting chemical liquid or chemical mist to the surface of the substrate to remove scum or burrs in a recessed area of the substrate before forming a chemical liquid layer with few bubbles or no bubbles on the substrate, and the scum and burrs absorb bubbles. The device as described in claim 10, wherein the vacuum degree of the first chamber is set at 25 Torr or above. The device as described in claim 10 further includes a rotational drive device configured to be connected to the substrate holding device. A substrate cleaning device comprises: a chamber, configured to be connected to a pump to form a vacuum environment in the chamber; a substrate holding device, configured to be arranged in the chamber to hold a substrate; at least one nozzle, configured to provide a pre-wetting chemical liquid or chemical mist to the surface of the substrate after the vacuum environment is formed in the chamber to form a chemical liquid layer with few bubbles or no bubbles on the substrate; an ultrasonic or megasonic device, configured to clean the substrate; and a pre-treatment unit, configured to remove scum or burrs in a recessed area of the substrate before providing a pre-wetting chemical liquid or chemical mist to the surface of the substrate to form a chemical liquid layer with few bubbles or no bubbles on the substrate, wherein the scum and burrs absorb bubbles. The device as described in claim 13, wherein the vacuum degree is set at 25 Torr or above. A substrate cleaning device comprises: a first chamber, configured to be connected to a vaporization unit, the vaporization unit being configured to convert a pre-wetting chemical solution into a gaseous state; a substrate holding device, configured to be arranged in the first chamber to hold a substrate; at least one nozzle, configured to be connected to the vaporization unit to provide vaporized liquid molecules to the substrate surface to form a pre-wetting chemical liquid layer with few bubbles or no bubbles on the substrate; a second chamber, configured with an ultrasonic or megasonic device to clean the substrate; and a pre-treatment unit, configured to provide a pre-wetting chemical liquid or chemical mist to the substrate surface to remove scum or burrs in a recessed area of the substrate before forming a chemical liquid layer with few bubbles or no bubbles on the substrate, the scum and burrs adsorbing bubbles. A substrate cleaning device comprises: a chamber; a vaporization unit configured to convert a pre-wetting chemical solution into a gaseous state; a substrate holding device configured to be arranged in the chamber to hold a substrate; at least one nozzle configured to be connected to the vaporization unit to provide vaporized liquid molecules to the substrate surface to form a pre-wetting chemical liquid layer with few bubbles or no bubbles on the substrate; at least one nozzle configured to provide a cleaning chemical liquid or chemical mist to the substrate surface to clean the substrate; an ultrasonic or megasonic device configured to clean the substrate; and a pre-treatment unit configured to provide a pre-wetting chemical liquid or chemical mist to the substrate surface to remove scum or burrs in the recessed area of the substrate before forming a chemical liquid layer with few bubbles or no bubbles on the substrate, and the scum and burrs absorb bubbles. A substrate cleaning method includes: placing a substrate on a substrate holding device; performing a pre-wetting process with few bubbles or no bubbles on the substrate, wherein the pre-wetting process with few bubbles or no bubbles includes: establishing a vacuum environment around the substrate, and then providing a pre-wetting chemical solution or chemical mist to the substrate; performing an ultrasonic or megasonic cleaning process to clean the substrate; before performing the pre-wetting process with few bubbles or no bubbles on the substrate, removing scum or burrs to improve the surface smoothness of the recessed area of the substrate, and the scum and burrs absorb bubbles. The method as claimed in claim 17, wherein the vacuum degree is set at 25 Torr or above.

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