TWI828723B - Methods and apparatus for cleaning substrates - Google Patents

Abstract

The present invention discloses a substrate cleaning method comprising the steps of: placing a substrate on a substrate holder; delivering cleaning liquid onto the surface of the substrate; implementing a pre-treatment process to detach bubbles from the surface of the substrate; and then implementing an ultra or mega sonic cleaning process for cleaning the substrate.

Description

Substrate cleaning method and device

The present invention relates to a method and device for cleaning a substrate, and more specifically, to separating bubbles from the surface of the substrate to avoid destructive implosion of the bubbles during the cleaning process, thereby more effectively removing tiny particles in pattern structures on the substrate.

Semiconductor devices are made by forming transistors and interconnects on a semiconductor substrate through a series of different processing steps. In recent years, the construction of transistors has developed from two dimensions to three dimensions, such as fin field effect transistors and 3D NAND memories. In order to enable the transistor terminals to be electrically connected to the semiconductor substrate, conductive (eg metal) grooves, holes and other similar structures need to be made on the dielectric material of the semiconductor substrate as part of the semiconductor device. Slots and holes carry electrical signals and energy between transistors, internal circuits, and external circuits.

In order to form fin field effect transistors and interconnect structures on a semiconductor substrate, the semiconductor substrate needs to go through multiple steps, such as masking, etching and deposition to form the required electronic circuits. In particular, multi-layer masking and plasma etching steps can form patterns of fin field effect transistors, 3D NAND flash memory cells and/or recessed areas in dielectric layers of a semiconductor substrate as Fins of transistors and/or slots and vias of interconnect structures. Wet cleaning is required to remove particles and contaminants in fin structures and/or trenches and vias during etching or photoresist ashing. In particular, as device fabrication nodes extend to 16 or 14nm and beyond, fin and/or sidewall losses of trenches and vias are key to maintaining critical dimensions. To reduce or eliminate sidewall losses, it is important to apply mild, dilute chemicals, or sometimes just deionized water. However, dilute chemicals or deionized water are generally not effective in removing particles within the fin structure, 3D NAND pores, and/or slots and vias. Therefore, mechanical forces, such as ultrasonic or megasonic waves, are required to effectively remove these particles. Ultrasonic waves or megasonic waves will generate cavitation oscillations to provide mechanical force to the substrate structure. These violent cavitation oscillations, such as unstable cavitation oscillations or micro-jet, will damage these pattern structures. Maintaining stable or controllable cavitation oscillation is a key parameter to control the limit of mechanical force damage and effectively remove particles.

1A and 1B illustrate that during the cleaning process, unstable cavitation oscillation damages the pattern structure 1030 on the substrate 1010. Unstable cavitation oscillations may be generated by the acoustic energy used to clean the substrate 1010. As shown in FIGS. 1A and 1B , the microjet generated 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 will damage the pattern on the substrate 1010 Structure 1030, especially as the feature size t shrinks to 70 nm or less.

Damage to the substrate pattern structure caused by micro-jet 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 distortion of the 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 of the substrate still occurs, and the number of damage is only a few (less than 100 ). However, in ultrasonic or megasonic assisted cleaning processes, the number of bubbles is often in the tens of thousands. The amount of damage to the substrate pattern structure does not match the number of bubbles, and the mechanism of this phenomenon is not yet clear.

According to one aspect of the present invention, a substrate cleaning method is disclosed, including the following steps: placing the substrate on a substrate holder; delivering cleaning liquid to the substrate surface; implementing a pretreatment process to separate air bubbles from the substrate surface; and implementing ultrasonic or megasonic waves. Sonic cleaning process to clean substrates.

According to another aspect of the present invention, a substrate cleaning device is disclosed, including: a substrate holder configured to hold the substrate; at least one liquid inlet configured to deliver cleaning liquid to the substrate surface; an ultrasonic or megasonic device configured To deliver acoustic energy to the cleaning fluid; one or more controllers configured to: control the ultrasonic or megasonic device to have a first power to perform a pretreatment process to separate bubbles from the substrate surface, and control the ultrasonic or megasonic device to have a first power The second power is used to implement an ultrasonic or megasonic cleaning process to clean the substrate, and the second power is higher than the first power.

According to yet another aspect of the present invention, a substrate cleaning device is disclosed, including: a substrate holder configured to hold a substrate; one or more The liquid inlet is configured to deliver a cleaning liquid to the substrate surface to clean the substrate, and to deliver a chemical solution to the substrate surface to implement a pretreatment process to separate bubbles from the substrate surface; an ultrasonic or megasonic device is configured to transmit sound to the cleaning liquid Can clean the substrate.

1010‧‧‧Substrate

1030‧‧‧Pattern structure

1050‧‧‧Bubbles

1303‧‧‧Ultrasonic or megasonic devices

1304‧‧‧Piezoelectric sensor

1306‧‧‧Vertical drive module

1307‧‧‧Arm

1308‧‧‧Acoustic Resonator

1310‧‧‧Substrate

1312‧‧‧Nozzle

1314‧‧‧Substrate holder

1316‧‧‧Rotation drive module

1370‧‧‧Cleaning fluid (chemical solution)

1388‧‧‧Controller

2010‧‧‧Substrate

2030‧‧‧Pattern Structure

2050‧‧‧Bubbles

2052‧‧‧Bubbles

3010‧‧‧Substrate

3030‧‧‧Pattern structure

3050‧‧‧Bubbles

3051‧‧‧Bubble implosion

3070‧‧‧Cleaning fluid

4010‧‧‧Substrate

4030‧‧‧Pattern structure

4050‧‧‧Bubbles

4070‧‧‧Cleaning fluid

5010‧‧‧Substrate

5030‧‧‧Pattern structure

5050‧‧‧Bubbles

5090‧‧‧Impurities

6030‧‧‧Pattern structure

6050‧‧‧Bubbles

6090‧‧‧Impurities

7010‧‧‧Substrate

7030‧‧‧Pattern structure

7052‧‧‧Bubbles

7054‧‧‧Bubbles

7056‧‧‧Bubbles

7070‧‧‧Cleaning fluid

7090‧‧‧Particles

8010‧‧‧Substrate

8030‧‧‧Pattern structure

8052‧‧‧Bubbles

8054‧‧‧Bubbles

8056‧‧‧Bubbles

8070‧‧‧Chemical solution

8090‧‧‧Particles

F1‧‧‧Ultrasonic or megasonic pressure acting on the bubble

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

F1”‧‧‧produces implosion force acting on the cleaning fluid

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

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

F2”‧‧‧The force acting on the substrate

F3‧‧‧When the bubble presses on the side wall of the graphic structure, the reaction force acting on the bubble is generated by the side wall of the graphic structure.

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

F3”‧‧‧The force acting on the side wall of the pattern structure

D1‧‧‧Solid surface direction of patterned structure

D2‧‧‧Solid surface direction of substrate 4010

f1‧‧‧Mechanical force generated by cavitation oscillation

f2‧‧‧Mechanical force generated by cavitation oscillation

f3‧‧‧Mechanical force generated by cavitation oscillation

1A and 1B reveal a schematic diagram of unstable cavitation oscillation damaging the pattern structure on the substrate during the cleaning process.

2A to 2D reveal schematic diagrams of damage to the pattern structure caused by implosion of bubbles attached to the surface of the pattern structure on the substrate.

3A to 3H reveal a schematic diagram of the mechanism of damage to the pattern structure caused by implosion of bubbles attached to the surface of the pattern structure on the substrate.

4A to 4B reveal schematic diagrams of an exemplary method of separating bubbles from the surface of a pattern structure on a substrate, wherein the bubbles adhere to the surface of the pattern structure and the substrate.

5A to 5C reveal schematic diagrams of an exemplary method of separating bubbles from the surface of a pattern structure on a substrate, wherein the bubbles are attached to impurities.

6A to 6C reveal schematic diagrams of another exemplary method of separating bubbles from the surface of a pattern structure on a substrate, wherein the bubbles are attached to impurities.

7A-7B disclose schematic diagrams of an exemplary method of separating bubbles from the surface of a patterned structure on a substrate, wherein the bubbles are attached to particles.

8A to 8B reveal schematic diagrams of another exemplary method of separating bubbles from the surface of a patterned structure on a substrate, wherein the bubbles are attached to particles.

Figure 9 discloses a schematic diagram of an exemplary method of cleaning a substrate according to the present invention.

Figure 10 discloses a schematic diagram of another exemplary method of cleaning a substrate according to the present invention.

Figure 11 discloses a schematic diagram of yet another exemplary method of cleaning a substrate according to the present invention.

Figure 12 reveals a schematic diagram of yet another exemplary method of cleaning a substrate according to the present invention.

13A to 13B reveal a schematic diagram of an exemplary device for cleaning a substrate according to the present invention.

Referring to FIG. 2A , in the process of using ultrasonic waves or megasonic waves to assist in substrate cleaning, there is a phenomenon that even if the power intensity of the ultrasonic waves or megasonic waves used to clean the substrate 2010 is reduced to a very low level (almost no particle removal rate), Damage to the pattern structure 2030 on the substrate 2010 may still occur. Furthermore, it is typically a single wall of the pattern structure 2030 that is damaged. Figure 2A illustrates two damage scenarios. One example is when a single wall of the pattern structure 2030 peels off to one side. As another example, a portion of a single wall of pattern structure 2030 is removed. Although Figure 2A illustrates two examples, it should be recognized that other similar damage may occur. What causes these damages?

Referring to FIGS. 2B to 2D , during the cleaning process of the substrate, small bubbles 2050 and 2052 tend to adhere to the solid surface, such as the substrate 2010 The surface or sidewall of the pattern structure 2030, as shown in Figures 2B and 2C. When bubbles 2050 and 2052 are attached to the surface of the substrate 2010 or the side wall 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 side wall of the pattern structure 2030. Once these bubbles 2050 , 2052 implosion occurs, and the pattern structure 2030 is peeled off from the sub-layer of the substrate 2010 toward the direction in which the bubble implosion force acts on the single side wall or a part of the single side wall of the pattern structure 2030 is removed, as shown in FIG. 2A . Although the bubble implosion is not as violent as micro-jet, 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 still damage the pattern structure 2030.

Additionally, in wet processes, small bubbles may coalesce into larger bubbles. Since bubbles tend to adhere to solid surfaces, the coalescence of bubbles on solid surfaces such as pattern structures and substrates increases the risk of bubble implosion occurring on pattern structures, especially in critical geometric sections.

3A to 3H describe the mechanism by which the pattern structure on the substrate is damaged by the implosion of bubbles attached to the substrate during ultrasonic or ultrasonic-assisted wet cleaning according to the present invention. FIG. 3A illustrates that the cleaning liquid 3070 is delivered to the surface of the substrate 3010 including the pattern structure 3030, and at least one bubble 3050 is attached to the bottom corner of the pattern structure 3030. In the positive ultrasonic or megasonic sound pressure working process shown in Figure 3B, F1 is the ultrasonic or megasonic pressure acting on the bubble 3050, and F2 is the pressure produced by the substrate 3010 when the bubble 3050 is pressed on the substrate 3010. The reaction force on the bubble 3050, F3, is the reaction force generated by the side wall of the graphic structure 3030 that acts on the bubble 3050 when the bubble 3050 presses against the side wall of the graphic structure 3030. In Figure 3C During the ultrasonic or megasonic negative sound pressure operation process shown in Figure 3D, the bubble 3050 expands due to the negative force of the ultrasonic or megasonic stretching of the bubble 3050. During the volume expansion of the bubble, 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 pattern structure 3030. After several cycles of alternating positive and negative sound pressures of ultrasonic or megasonic waves, the temperature of the gas in the bubble becomes higher and higher, the volume of the bubble becomes larger and larger, and finally bubble implosion 3051 occurs, which acts on the cleaning fluid. The implosion force F1" on 3070, the force F2" acting on the substrate 3010, and the force F3" acting on the side wall of the pattern structure 3030, as shown in Figure 3G. The implosion force causes the side wall of the pattern structure 3030 to be damaged, as shown in Figure 3H shown.

In order to avoid damage to the pattern structure on the substrate due to bubble implosion during ultrasonic or megasonic assisted wet cleaning, preferably, the bubbles are removed from the surface of the pattern structure before applying sonic energy to the cleaning solution to clean the substrate. separated from the substrate.

Various methods for isolating bubbles from patterned structure surfaces and substrates are revealed below.

4A and 4B reveal an embodiment of substrate pretreatment according to the present invention to separate bubbles from the surface of a pattern structure on the substrate. When the cleaning liquid 4070 is delivered to the surface of the substrate 4010 including the pattern structure 4030, at least one bubble 4050 is attached to the bottom corner of the pattern structure 4030, as shown in FIG. 4A. Therefore, bubble separation pretreatment is required before using ultrasonic or megasonic waves to clean substrates. In the bubble separation pretreatment process, a method, such as increasing surface moistening of the pattern structure 4030 from the solid surface direction D1 along the pattern structure 4030 and the solid surface direction D2 of the substrate 4010, respectively. wetness, or use minimum mechanical force to interfere from the direction D1 and the direction D2, so that the interface between the surface of the pattern structure 4030 and the bubble 4050 and the interface between the surface of the substrate 4010 and the bubble 4050 gradually shrink, so as to achieve the desired effect from the pattern structure 4030 The purpose is to separate bubbles on the surface and substrate 4010, as shown in Figure 4B.

One embodiment of the bubble separation pretreatment process according to the present invention is to change the surface of the substrate 4010 from hydrophobicity to hydrophilicity by providing a chemical solution on the surface of the substrate 4010, for example, providing a chemical solution to form a hydrophilic coating on the surface of the substrate 4010 , or use chemical solutions such as ozone solution or SC1 solution (a mixture of ammonium hydroxide, hydrogen peroxide, water) to oxidize hydrophobic surface materials such as silicon or polycrystalline silicon layers into hydrophilic silicon oxide layers.

According to one embodiment of the bubble separation pretreatment process of the present invention, a chemical solution containing surfactants, additives or chelating agents is provided to the surface of the substrate 4010 . A chemical solution containing surfactants, additives or chelating agents can increase the wettability of the chemical solution on the surface of the substrate 4010, thereby separating bubbles attached to the surface of the pattern structure 4030 and the substrate 4010. Chemicals such as carboxyl-containing ethylenediaminetetraacetic acid (EDTA), tetracarboxyethylenediaminetetrapropionic acid (EDTP) acid/salt, etc. are used as surfactants doped in chemical solutions to improve the wettability of chemical solutions.

In addition, low-power ultrasonic waves or megasonic waves can be incorporated into the above embodiments to improve bubble separation efficiency. Low-power ultrasonic waves or megasonic waves generate small mechanical forces that contribute to stable cavitation oscillation, thereby generating mechanical forces to separate the bubbles 4050 from the surface of the pattern structure 4030 and the surface of the substrate 4010. Low power ultrasound or megasonic waves can operate in continuous mode (non-pulsed mode) and the power density can be, for example, 1 mw/cm ² -15 mw/cm ² . The duration of applying low-power ultrasonic waves or megasonic waves in a continuous mode to the cleaning solution to separate bubbles from the surface of the pattern structure 4030 and the surface of the substrate 4010 may be, for example, 10s-60s. Patent application No. PCT/CN2008/073471, filed on December 12, 2008, discloses a more detailed description of the application of continuous mode ultrasonic or megasonic waves to cleaning fluids, all of which are incorporated herein by reference. Low power ultrasonic or megasonic waves can be operated in pulse mode and the power density can be, for example, 15 mw/cm ² -200 mw/cm ² . The duration of applying low-power ultrasonic waves or megasonic waves with a pulse mode into the cleaning solution to separate bubbles from the surface of the pattern structure 4030 and the surface of the substrate 4010 may be, for example, 10s-120s. Patent application No. PCT/CN2015/079342, filed on May 20, 2015, discloses a more detailed description of the application of pulsed mode ultrasonic or megasonic waves to cleaning fluids, all of which are incorporated herein by reference.

Referring to FIGS. 5A to 5C , it is revealed that one embodiment of the bubble separation pretreatment process according to the present invention is to remove impurities attached to the surface of the substrate, such as metal impurities, organic pollutants and polymer residues. Bubbles 5050 are easily attached around impurities 5090 such as metal impurities, organic pollutants, and polymer residues on the surface of the substrate 5010. Therefore, the bubbles 5050 attached to the pattern structure 5030 and the surface of the substrate 5010 may have problems during the subsequent ultrasonic or megasonic cleaning process. Risk of imploding and damaging pattern structure 5030 on substrate 5010. A pretreatment method that provides a chemical solution on the surface of a substrate 5010 to help remove impurities 5090 such as metal impurities and polymer residues from the surface of the substrate 5010 prior to an ultrasonic or megasonic cleaning process, e.g. Use ozone solution to oxidize the surface polymer residue, or use high temperature (90-150°C) SPM solution (sulfuric acid, hydrogen peroxide mixture) to carbonize the surface polymer residue. In another example, chemicals such as EDTA can also be used to chelate surface metal ions to remove metal impurities.

In some cases, when impurities 5090 such as organic pollutants or polymer residues accumulate at the corners of the pattern structure 5030, due to poor wettability of the chemical solution on the surface of the impurities 5090, the bubbles 5050 are easily attached to the impurities 5090, which may This results in a destructive implosion on the surface of the pattern structure 5030. Two methods of removing impurities 5090 and separating accumulated air bubbles 5050 are disclosed below. In one embodiment, a chemical solution is used to remove impurities 5090 in the pretreatment step, as shown in Figure 5A using ozone solution or SC1 solution to remove organic pollutants. As the chemical solution reacts with the impurity 5090, the impurity 5090 is shrinking in size, as shown in Figure 5B. As the impurities 5090 are removed from the surface of the pattern structure 5030 and the substrate 5010, the wettability of the chemical solution increases, causing the bubbles 5050 to leave the surface of the pattern structure 5030, as shown in Figure 5C.

Referring to FIGS. 6A to 6C , according to another embodiment of the present invention, in the pretreatment step, a low-power ultrasonic or megasonic wave process is used to improve the removal efficiency of impurities 6090, such as using ozone solution or SC1 solution to remove organic pollution. object, as shown in Figure 6A. Due to the application of low-power ultrasonic waves or megasonic waves, the volume of the bubble 6050 alternately expands and contracts, thereby allowing the impurities 6090 to fully contact the chemical solution and further react with the chemical solution. This process accelerates the reaction efficiency of the chemical solution with impurities 6090. As impurities 6090 are removed from the surface of pattern structure 6030, the wettability of the chemical solution increases causing bubbles 6050 to leave the surface of pattern structure 6030, as shown in Figure 6C. Low power ultrasound or megasonic waves can operate in continuous mode (non-pulsed mode) and the power density can be, for example, 1 mw/cm ² -15 mw/cm ² . Low power ultrasonic or megasonic waves can also be operated in pulsed mode and the power density can be, for example, 15 mw/cm ² -200 mw/cm ² .

7A and 7B reveal an embodiment of separating bubbles from the surface of a pattern structure on a substrate according to the present invention. If the particles 7090 are trapped in the corners of the pattern structure 7030 of the substrate 7010, air bubbles 7052, 7054, 7056 are more likely to accumulate around the surface of the particles 7090 due to the irregular shape of the particles. The bubbles 7052, 7054, and 7056 attached to the surface of the pattern structure 7030 and the surface of the particles 7090 have the risk of imploding and damaging the pattern structure 7030. Therefore, before performing ultrasonic or megasonic cleaning processes, particle removal and bubble separation pretreatment processes are required.

As shown in FIGS. 7A and 7B , in the pretreatment process, particles 7090 are first removed to further separate bubbles 7052 , 7054 , and 7056 from the surface of the pattern structure 7030 and the surface of the substrate 7010 . Before the ultrasonic or megasonic cleaning process, low-power ultrasonic or megasonic waves may be applied to the cleaning liquid 7070 to remove particles 7090 and separate bubbles 7052, 7054, and 7056 from the surface of the pattern structure 7030 and the surface of the substrate 7010. Low-power ultrasonic waves or megasonic waves generate cavitation oscillations on the bubbles 7052, 7054, and 7056. The mechanical forces f1, f2, f3 and the resultant force F generated by the cavitation oscillation of the bubbles 7052, 7054, 7056 push the particles 7090 outward, as shown in Figure 7A. The particles 7090 are finally pushed upward, and the oscillation force of the air pockets of the bubbles 7052, 7054, and 7056 will also generate acoustic agitation to separate the bubbles 7052, 7054, and 7056 from the surface of the pattern structure 7030 and the surface of the substrate 7010. Low-power ultrasound or megasonic waves can operate in continuous mode (non-pulse mode), and the power density can be, for example, 1 mw/cm ² -15 mw/cm ² . Low power ultrasonic or megasonic waves can also be operated in pulsed mode and the power density can be, for example, 15 mw/cm ² -200 mw/cm ² .

8A and 8B reveal another embodiment of separating bubbles from the surface of a pattern structure on a substrate according to the present invention. In the pretreatment process, the particles 8090 are removed by providing a chemical solution 8070 on the surface of the substrate 8010 to react with the particles 8090 or dissolve the particles 8090, so as to further separate the bubbles 8052, 8054, and 8056 from the surface of the pattern structure 8030 and the surface of the substrate 8010. The chemical solution can be an ozone solution or SC1 solution, which oxidizes the polymer particles. In this process, low-power ultrasonic or megasonic processes can also be used to assist chemical reactions or dissolution before subsequent ultrasonic or megasonic cleaning processes. Low-power ultrasonic or megasonic waves generate cavitation oscillations on bubbles 8052, 8054, 8056 surrounding particles 8090 trapped in the corners of pattern structure 8030. The mechanical forces f1, f2, f3 and the resultant force F generated by the cavitation oscillation of the bubbles 8052, 8054, and 8056 push the particles 8090 outward. The chemical solution reacts or dissolves the particles 8090 and combines with the mechanical force generated by low-power ultrasonic or megasonic waves to eventually push the particles 8090 upward. The oscillation force of the air pockets of the bubbles 8052, 8054, and 8056 will also generate acoustic agitation to separate the bubbles 8052, 8054, and 8056 from the surface of the pattern structure 8030 and the surface of the substrate 8010.

The invention discloses a substrate cleaning method, which includes the following steps:

Place the substrate on the substrate holder;

Deliver cleaning fluid to the substrate surface;

Implementing a pretreatment process to separate air bubbles from the substrate surface; and

Implement ultrasonic or megasonic cleaning processes to clean substrates.

The duration of performing the pretreatment process is 5 seconds or more.

Figure 9 reveals an embodiment of a substrate cleaning method according to the present invention. In this embodiment, ultrasonic or megasonic waves operating in pulsed mode are applied in the pretreatment process to detach bubbles from the substrate surface. The ultrasonic wave or megasonic wave has a first power, and the power density may be, for example, 15 mw/cm ² -200 mw/cm ² . The duration of application of pulsed mode low-power ultrasound or megasonic waves to separate the bubbles may be, for example, 10s-120s. After detaching the bubbles from the substrate surface, ultrasonic or megasonic waves operating in pulse mode are then applied to implement an ultrasonic or megasonic cleaning process to clean the substrate. The ultrasonic wave or megasonic wave has a second power, the second power is higher than the first power, and the power density of the second power may be, for example, 0.2w/cm ² -2w/cm ² . The duration of applying high-power ultrasonic waves or megasonic waves in pulse mode to clean the substrate may be, for example, within 600 s.

Figure 10 reveals another embodiment of a substrate cleaning method according to the present invention. In this embodiment, ultrasonic or megasonic waves operating in continuous mode (non-pulsed mode) are applied to the pretreatment process to separate bubbles from the substrate surface. The ultrasonic wave or megasonic wave has a first power, and the power density may be, for example, 1 mw/cm ² -15 mw/cm ² . The duration of applying continuous mode low-power ultrasonic or megasonic waves to separate the bubbles may be, for example, 10s-60s. After detaching the bubbles from the substrate surface, ultrasonic or megasonic waves operating in pulse mode are then applied to implement an ultrasonic or megasonic cleaning process to clean the substrate. The ultrasonic wave or megasonic wave has a second power, the second power is higher than the first power, and the power density of the second power may be, for example, 0.2w/cm ² -2w/cm ² . The duration of applying high-power ultrasonic waves or megasonic waves in pulse mode to clean the substrate may be, for example, within 600 s.

Figure 11 reveals yet another embodiment of a substrate cleaning method according to the present invention. In this embodiment, ultrasonic or megasonic waves operating in pulsed mode are applied in the pretreatment process to detach bubbles from the substrate surface. The ultrasonic wave or megasonic wave has a first power, and the power density may be, for example, 15 mw/cm ² -200 mw/cm ² . The duration of application of pulsed mode low-power ultrasound or megasonic waves to separate the bubbles may be, for example, 10s-120s. After detaching the bubbles from the substrate surface, ultrasonic or megasonic waves operating in a continuous mode (non-pulsed mode) are subsequently applied to implement an ultrasonic or megasonic cleaning process to clean the substrate. The ultrasonic wave or megasonic wave has a second power, the second power is higher than the first power, and the power density of the second power may be, for example, 15 mw/cm ² -500 mw/cm ² . The duration t2 of applying continuous mode high-power ultrasonic or megasonic cleaning of the substrate may be, for example, 10s-60s. During the t2 time period, bubble implosion or unstable cavitation oscillation may occur. However, since it occurs above the structure, the impact force generated by the micro-jet may not damage the pattern structure on the substrate.

Figure 12 reveals yet another embodiment of the substrate cleaning method according to the present invention. In this embodiment, ultrasonic or megasonic waves operating in continuous mode (non-pulsed mode) are applied in the pretreatment process to separate bubbles from the substrate surface. The ultrasonic wave or megasonic wave has a first power, and the power density may be, for example, 1 mw/cm ² -15 mw/cm ² . The duration of application of continuous mode low-power ultrasonic or megasonic waves to separate the bubbles may be, for example, 5s-60s. After detaching the bubbles from the substrate surface, ultrasonic or megasonic waves operating in a continuous mode (non-pulsed mode) are subsequently applied to implement an ultrasonic or megasonic cleaning process to clean the substrate. The ultrasonic wave or megasonic wave has a second power, the second power is higher than the first power, and the power density of the second power may be, for example, 15 mw/cm ² -500 mw/cm ² . The duration of applying continuous mode high-power ultrasonic or megasonic cleaning of the substrate may be, for example, 10s-120s.

The pretreatment method for separating bubbles disclosed in FIGS. 4A to 8B can be applied or combined with the method disclosed in FIGS. 9 to 12 .

Referring to FIGS. 13A and 13B , an embodiment of a substrate cleaning device according to the present invention is disclosed. 13A is a cross-sectional view of the substrate cleaning device. The substrate cleaning device includes: a substrate holder 1314 for holding the substrate 1310, a rotation driving module 1316 for driving the substrate holder 1314, and transporting cleaning liquid and chemical solution 1370 to the surface of the substrate 1310. Nozzle 1312. The substrate cleaning device also includes an ultrasonic or megasonic device 1303 located above the substrate 1310 . The ultrasonic or megasonic device 1303 further includes a piezoelectric sensor 1304 and an acoustic resonator 1308 paired therewith. The piezoelectric sensor 1304 acts like a vibration when energized, and the acoustic resonator 1308 transmits low or high acoustic energy to the cleaning fluid or chemical solution. The bubble cavitation oscillation generated by the low sound energy causes the bubbles to detach from the substrate 1310 surface. The bubble cavitation oscillation generated by high acoustic energy vibrates and loosens contaminants such as impurity particles on the surface of the substrate 1310 to remove them.

Referring again to Figure 13A, the substrate cleaning device also includes an arm 1307 connected to the ultrasonic or megasonic device 1303. The arm 1307 is used to move the ultrasonic or megasonic device 1303 in the vertical direction Z, thereby changing the liquid film thickness. d. The vertical driving module 1306 drives the arm 1307 to move vertically. Both the vertical driving module 1306 and the rotating driving module 1316 are controlled by the controller 1388 .

FIG. 13B is a top view of the substrate cleaning device shown in FIG. 13A. The ultrasonic or megasonic device 1303 covers only a small area of the substrate 1310 and therefore requires rotation to obtain uniform sonic energy across the entire substrate 1310. Although only one ultrasonic or megasonic device 1303 is shown in Figures 13A and 13B, in other embodiments, two or more sonic devices may be used simultaneously or intermittently. Similarly, two or more nozzles 1312 may be used to deliver cleaning liquid or chemical solution to the surface of the substrate 1310 respectively.

In some aspects of the invention, the rotation of the substrate holder and the application of acoustic energy may be controlled by one or more controllers, such as software programmable control of the device. The one or more controllers may also include one or more timers to control the timing of rotation and/or energy application.

To sum up, the present invention has specifically disclosed the relevant technology through the above embodiments and related drawings, so that those skilled in the art can implement it accordingly. The above-mentioned embodiments are only used to illustrate the present invention, but not to limit the present invention. The scope of rights of the present invention should be defined by the patent application scope of the present invention. Any change in the number of elements described herein or the substitution of equivalent elements shall still fall within the scope of the present invention.

4010‧‧‧Substrate

4030‧‧‧Pattern structure

4050‧‧‧Bubbles

4070‧‧‧Cleaning fluid

D1‧‧‧Solid surface direction of patterned structure

D2‧‧‧Solid surface direction of substrate 4010

Claims (25)

A substrate cleaning method includes: placing the substrate on a substrate holder; delivering cleaning liquid to the surface of the substrate; implementing a pretreatment process to separate air bubbles from the surface of the substrate; and implementing an ultrasonic or megasonic cleaning process to clean the substrate. The method of claim 1, wherein the duration of performing the pretreatment process is 5 seconds or more. The method of claim 1, wherein the step of implementing a pretreatment process to separate air bubbles from the substrate surface includes changing the substrate surface from hydrophobic to hydrophilic by providing a chemical solution to form a hydrophilic coating on the substrate surface. The method of claim 1, wherein the step of implementing a pretreatment process to separate air bubbles from the substrate surface includes changing the substrate surface from hydrophobic to hydrophilic by providing a chemical solution to oxidize the hydrophobic substrate surface into a hydrophilic oxide layer . The method of claim 1, wherein the step of implementing a pretreatment process to separate bubbles from the substrate surface includes providing a chemical solution on the substrate surface to increase the wettability of the chemical solution on the substrate surface. The method of claim 1, wherein the step of implementing a pretreatment process to separate bubbles from the substrate surface includes applying ultrasonic waves or megasonic waves with a first power to the cleaning liquid to generate stable bubble cavitation oscillations. The method of claim 6, wherein the ultrasonic wave or megasonic wave operates in a continuous mode or a pulse mode. The method of claim 1, wherein the step of implementing a pretreatment process to separate bubbles from the surface of the substrate includes removing impurities attached to the surface of the substrate. The method of claim 8, wherein a chemical solution is used to remove impurities on the surface of the substrate. The method of claim 9, further comprising applying ultrasonic waves or megasonic waves with a first power to the chemical solution to generate stable bubble cavitation oscillations. The method of claim 10, wherein the ultrasonic wave or megasonic wave operates in a continuous mode or a pulse mode. The method of claim 1, wherein the step of implementing a pretreatment process to separate bubbles from the substrate surface includes removing particles and then separating the bubbles from the substrate surface. The method of claim 12, wherein ultrasonic waves or megasonic waves with a first power are applied to the cleaning liquid to remove particles and separate bubbles from the substrate surface. The method of claim 13, wherein the ultrasonic wave or megasonic wave operates in a continuous mode or a pulse mode. The method of claim 12, wherein a chemical solution is provided to the surface of the substrate to react or dissolve the particles. The method of claim 1, wherein the step of implementing an ultrasonic or megasonic cleaning process to clean the substrate includes applying ultrasonic or megasonic waves with a second power to implement an ultrasonic or megasonic cleaning process to clean the substrate, the ultrasonic wave or megasonic operating in continuous mode or pulsed mode. A substrate cleaning device, including: a substrate holder configured to hold the substrate; at least one liquid inlet configured to deliver cleaning liquid to the surface of the substrate; an ultrasonic or megasonic device configured to transmit sound energy to the cleaning liquid; a or a plurality of controllers configured to: control the ultrasonic or megasonic device to have a first power to perform a pretreatment process to separate bubbles from the substrate surface, and The ultrasonic or megasonic device is controlled to have a second power to implement an ultrasonic or megasonic cleaning process to clean the substrate, and the second power is higher than the first power. The device of claim 17, wherein the ultrasonic or megasonic device operates in a continuous mode or a pulsed mode. The device of claim 17, wherein the liquid inlet delivers a chemical solution to change the surface of the substrate from hydrophobic to hydrophilic to separate bubbles from the surface of the substrate. The device of claim 17, wherein the liquid inlet delivers the chemical solution to the surface of the substrate to increase the wettability of the chemical solution on the surface of the substrate to separate bubbles from the surface of the substrate. The device of claim 17, wherein the liquid inlet delivers a chemical solution to remove impurities attached to the surface of the substrate to separate bubbles from the surface of the substrate. The device of claim 17, wherein the liquid inlet delivers a chemical solution to the surface of the substrate to react or dissolve particles to separate bubbles from the surface of the substrate. A substrate cleaning device includes: a substrate holder configured to hold the substrate; One or more liquid inlets configured to deliver a cleaning liquid to the substrate surface to clean the substrate, and to deliver a chemical solution to the substrate surface to implement a pretreatment process to separate bubbles from the substrate surface; an ultrasonic or megasonic device configured to The cleaning fluid delivers acoustic energy to clean the substrate. The device of claim 23, wherein the duration of performing the pretreatment process is 5 seconds or more. The device of claim 23, wherein the ultrasonic or megasonic device operates in a continuous mode or a pulsed mode.

Images