阅读说明：本技术 基板的清洗方法及装置 (Method and apparatus for cleaning substrate ) 是由 王晖 王希 张晓燕 陈福发 于 2018-01-23 设计创作，主要内容包括：本发明揭示了一种基板(2010、3010、4010、5010、6010、7010、8010)清洗方法,包括以下步骤：将基板(2010、3010、4010、5010、6010、7010、8010)放置在基板保持装置(1314)上；将清洗液输送到基板(2010、3010、4010、5010、6010、7010、8010)表面；实施预处理工艺以从基板(2010、3010、4010、5010、6010、7010、8010)表面分离气泡(2050、2052、3050、4050、5050、6050、7052、70584、7056、8052、8054、8056)；以及实施超声波或兆声波清洗工艺以清洗基板(2010、3010、4010、5010、6010、7010、8010)。(The invention discloses a method for cleaning substrates (2010, 3010, 4010, 5010, 6010, 7010 and 8010), which comprises the following steps: placing a substrate (2010, 3010, 4010, 5010, 6010, 7010, 8010) on a substrate holder (1314); delivering the cleaning solution to the surface of the substrate (2010, 3010, 4010, 5010, 6010, 7010, 8010); performing a pretreatment process to separate bubbles (2050, 2052, 3050, 4050, 5050, 6050, 7052, 70584, 7056, 8052, 8054, 8056) from a surface of a substrate (2010, 3010, 4010, 5010, 6010, 7010, 8010); and performing an ultrasonic or megasonic cleaning process to clean the substrate (2010, 3010, 4010, 5010, 6010, 7010, 8010).)

1. A method of cleaning a substrate, comprising:

placing a substrate on a substrate holding device;

delivering a cleaning fluid to the substrate surface;

performing a pre-treatment process to separate bubbles from the substrate surface; and

an ultrasonic or megasonic cleaning process is performed to clean the substrate.

2. The method of claim 1, wherein the pretreatment process is carried out for a duration of 5 seconds or more than 5 seconds.

3. The method of claim 1, wherein performing a pretreatment process to detach bubbles from the substrate surface comprises changing the substrate surface from hydrophobic to hydrophilic.

4. The method of claim 3, wherein the substrate surface is changed from hydrophobic to hydrophilic by providing a chemical solution to form a hydrophilic coating on the substrate surface.

5. The method of claim 3, wherein the substrate surface is changed from hydrophobic to hydrophilic by providing a chemical solution to oxidize the hydrophobic substrate surface to a hydrophilic oxide layer.

6. The method of claim 1, wherein performing a pretreatment process to detach gas bubbles from the substrate surface comprises providing a chemical solution on the substrate surface to increase wettability of the substrate surface with the chemical solution.

7. The method of claim 1, wherein performing a pretreatment process to detach bubbles from the surface of the substrate comprises applying ultrasonic or megasonic waves having a first power to the cleaning fluid to generate stable bubble cavitation oscillations.

8. The method of claim 7, wherein the ultrasonic or megasonic waves are operated in a continuous mode or a pulsed mode.

9. The method of claim 1, wherein performing a pretreatment process to separate bubbles from the surface of the substrate comprises removing impurities attached to the surface of the substrate.

10. The method of claim 9, wherein the impurities on the surface of the substrate are removed using a chemical solution.

11. The method of claim 10, further comprising applying ultrasonic or megasonic waves having a first power to the chemical solution to produce stable bubble cavitation oscillations.

12. The method of claim 11, wherein the ultrasonic or megasonic waves are operated in a continuous mode or a pulsed mode.

13. The method of claim 1, wherein the step of performing a pretreatment process to detach gas bubbles from the surface of the substrate comprises removing particles and then detaching gas bubbles from the surface of the substrate.

14. The method of claim 13, wherein the cleaning fluid is subjected to ultrasonic waves or megasonic waves having a first power to dislodge particles and detach bubbles from the surface of the substrate.

15. The method of claim 14, wherein the ultrasonic or megasonic waves are operated in a continuous mode or a pulsed mode.

16. The method of claim 13, wherein a chemical solution is provided to the substrate surface to react or dissolve the particles.

17. The method of claim 1, wherein performing an ultrasonic or megasonic cleaning process to clean the substrate comprises applying ultrasonic or megasonic cleaning process having a second power to clean the substrate, the ultrasonic or megasonic operating in a continuous mode or a pulsed mode.

18. A substrate cleaning apparatus, comprising:

a substrate holding device configured to hold a substrate;

at least one liquid inlet configured to deliver a cleaning liquid to the substrate surface;

an ultrasonic or megasonic device configured to impart sonic energy to the cleaning fluid;

one or more controllers configured to:

controlling the ultrasonic or megasonic device to have a first power to perform a pretreatment process to detach bubbles from the surface of the substrate, an

The ultrasonic or megasonic apparatus is controlled to have a second power to perform an ultrasonic or megasonic cleaning process to clean the substrate, the second power being higher than the first power.

19. The apparatus of claim 18, wherein the ultrasonic or megasonic apparatus operates in a continuous mode or a pulsed mode.

20. The apparatus of claim 18, wherein the loading port delivers a chemical solution to change the substrate surface from hydrophobic to hydrophilic to separate the gas bubbles from the substrate surface.

21. The apparatus of claim 18, wherein the loading port delivers the chemical solution to the substrate surface to increase wettability of the chemical solution on the substrate surface to separate the gas bubbles from the substrate surface.

22. The apparatus of claim 18, wherein the loading port delivers a chemical solution to remove impurities attached to the surface of the substrate to separate bubbles from the surface of the substrate.

23. The apparatus of claim 18, wherein the loading port delivers a chemical solution to the substrate surface to react or dissolve the particles to separate the gas bubbles from the substrate surface.

24. A substrate cleaning apparatus, comprising:

a substrate holding device configured to hold a substrate;

one or more fluid inlets configured to deliver a cleaning fluid to the substrate surface to clean the substrate and a chemical solution to the substrate surface to perform a pre-treatment process to detach gas bubbles from the substrate surface;

an ultrasonic or megasonic apparatus configured to impart sonic energy to the cleaning fluid to clean the substrate.

25. The apparatus of claim 24, wherein the pre-treatment process is performed for a duration of 5 seconds or more than 5 seconds.

26. The apparatus of claim 24, wherein the ultrasonic or megasonic apparatus operates in a continuous mode or a pulsed mode.

Technical Field

The present invention relates to a method and apparatus for cleaning a substrate, and more particularly, to separating bubbles from a surface of a substrate to prevent destructive implosion of the bubbles during cleaning, thereby more effectively removing fine particles in a pattern structure on the substrate.

Background

Semiconductor devices are fabricated by forming transistors and interconnect lines on a semiconductor substrate through a series of different processing steps. In recent years, the build-up of transistors has progressed from two dimensions to three dimensions, such as finfets and 3D NAND memories. In order to enable the transistor terminals to be electrically connected to the semiconductor substrate, conductive (e.g., metal) trenches, holes, and other similar structures need to be formed in the dielectric material of the semiconductor substrate as part of the semiconductor device. The slots and holes may transfer electrical signals and energy between transistors, internal circuitry, and external circuitry.

In order to form finfets and interconnect structures on a semiconductor substrate, the semiconductor substrate is subjected to a number of steps, such as masking, etching, and deposition, to form the desired electronic circuitry. In particular, the multi-masking and plasma etching steps may pattern fin field effect transistors, 3D NAND flash memory cells, and/or recessed regions in the dielectric layer of the semiconductor substrate as trenches and vias for the fins and/or interconnect structures of the transistors. Wet cleaning is required to remove particles and contaminants in the fin structure and/or trenches and vias during etching or photoresist ashing. In particular, as device fabrication nodes extend to 16 or 14nm and smaller, sidewall loss of fins and/or trenches and vias is critical to maintaining critical dimensions. To reduce or eliminate sidewall loss, it is important to use mild, dilute chemicals, or sometimes deionized water alone. However, dilute chemicals or deionized water are generally not effective in removing particulates within fin structures, 3D NAND holes, and/or trenches and vias. Therefore, it is necessary to use mechanical force, such as ultrasonic waves or megasonic waves, to effectively remove these particles. Ultrasonic or megasonic waves can generate cavitation oscillations that provide mechanical force to the substrate structure, and these violent cavitation oscillations, such as unstable cavitation oscillations or microjets, can damage these patterned structures. Maintaining stable or controlled cavitation oscillations is a key parameter in controlling the mechanical force damage limit and effectively removing particles.

Fig.1A and 1B depict unstable cavitation oscillations damaging a pattern structure 1030 on a substrate 1010 during cleaning. Unstable cavitation oscillations may be generated by the sonic energy used to clean the substrate 1010. As shown in fig.1A and 1B, the microjets generated by implosions of bubbles 1050 occur above the top of pattern 1030 and are very violent (up to several thousand atmospheres and several thousand degrees celsius), which can damage pattern 1030 on substrate 1010, especially as feature size t is reduced to 70nm or less.

Damage to the substrate pattern structure caused by microjets caused by implosion of bubbles is overcome by controlling cavitation oscillation of the bubbles during cleaning. Stable or controlled cavitation oscillations can be achieved over the entire substrate to avoid damage to the pattern structure, as disclosed in PCT/CN2015/079342, patent application number filed 5/20/2015.

In some cases, even if the power intensity of ultrasonic waves or megasonic waves used for cleaning the substrate is reduced to be low (almost no particle removal rate), damage of the substrate pattern structure occurs, and the number of damage is only a few (100 or less). However, in ultrasonic or megasonic assisted cleaning processes, the number of bubbles is typically tens of thousands. The mechanism of this phenomenon, in which the number of damages of the substrate pattern structure is not matched with the number of bubbles, is not clear.

Disclosure of Invention

According to one aspect of the present invention, a substrate cleaning method is disclosed, comprising the steps of: placing a substrate on a substrate holding device; delivering a cleaning fluid to the substrate surface; performing a pre-treatment process to separate bubbles from the substrate surface; and performing an ultrasonic or megasonic cleaning process to clean the substrate.

According to another aspect of the present invention, there is disclosed a substrate cleaning apparatus including: a substrate holding device configured to hold a substrate; at least one liquid inlet configured to deliver a cleaning liquid to the substrate surface; an ultrasonic or megasonic device configured to impart sonic energy to the cleaning fluid; one or more controllers configured to: the ultrasonic or megasonic apparatus is controlled to have a first power to perform a pretreatment process to detach bubbles from the surface of the substrate, and a second power higher than the first power to perform an ultrasonic or megasonic cleaning process to clean the substrate.

According to still another aspect of the present invention, there is disclosed a substrate cleaning apparatus including: a substrate holding device configured to hold a substrate; one or more fluid inlets configured to deliver a cleaning fluid to the substrate surface to clean the substrate and a chemical solution to the substrate surface to perform a pre-treatment process to detach gas bubbles from the substrate surface; an ultrasonic or megasonic apparatus configured to impart sonic energy to the cleaning fluid to clean the substrate.

Drawings

FIGS. 1A and 1B disclose schematic diagrams of unstable cavitation oscillations damaging pattern structures on a substrate during cleaning.

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

Fig.3A to 3H are schematic diagrams illustrating a mechanism of damaging a pattern structure by implosion of bubbles attached to a surface of the pattern structure on a substrate.

Fig. 4A-4B disclose schematic diagrams of an exemplary method for separating bubbles from a surface of a pattern structure on a substrate, wherein the bubbles are attached to the surface of the pattern structure and the substrate.

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

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

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

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

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

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

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

Fig.12 discloses a schematic view of yet another exemplary method of cleaning a substrate according to the present invention.

Fig. 13A-13B disclose schematic views of an exemplary apparatus for cleaning a substrate according to the present invention.

Detailed Description

Referring to fig.2A, in the substrate cleaning process using ultrasonic waves or megasonic waves for assistance, there is a phenomenon in which damage to the pattern structure 2030 on the substrate 2010 occurs even if the power intensity of the ultrasonic waves or megasonic waves for cleaning the substrate 2010 is reduced to a very low level (almost no particle removal rate). In addition, it is often the case that the single wall of the pattern structure 2030 is damaged. Fig.2A illustrates two damage scenarios. As an example, the single walls of the pattern structure 2030 are peeled off toward one side. As another example, a portion of the single wall of the pattern structure 2030 is removed. Although fig.2A illustrates two examples, it should be appreciated that other similar damage may occur. What is the cause of these damages?

Referring to fig.2B to 2D, during cleaning of the substrate, the small bubbles 2050, 2052 tend to adhere to a solid surface, such as the surface of the substrate 2010 or the sidewalls of the pattern structure 2030, as shown in fig.2B and 2C. When the bubbles 2050, 2052 adhere to the surface of the substrate 2010 or to the side walls of the pattern structure 2030, for example, the bubbles 2052 adhere to the bottom corners of the pattern structure 2030, the bubbles 2050 adhere to the single side walls of the pattern structure 2030, and once these bubbles 2050, 2052 implode, the pattern structure 2030 is peeled off from the sub-layers of the substrate 2010 or a part of the single side walls of the pattern structure 2030 is removed in the direction in which the force of the imploding of the bubbles acts on the single side walls, as shown in fig. 2A. Although the implosion of the bubbles is not as severe as the microjet, the pattern structure 2030 is still damaged by the energy generated by the implosion of the small bubbles due to the attachment of the bubbles 2050, 2052 to the surface of the substrate 2010 and the side walls of the pattern structure 2030.

Furthermore, in wet processes, small bubbles may coalesce into larger bubbles. The incorporation of bubbles on solid surfaces, such as pattern structures and substrates, increases the risk of bubble implosions occurring on the pattern structures, particularly in critical geometries, as the bubbles tend to adhere to the solid surface.

Fig.3A to 3H illustrate the mechanism by which implosion of bubbles attached to a substrate during ultrasonic or ultrasonic-assisted wet cleaning according to the present invention damages a pattern structure on the substrate. Fig.3A illustrates that a 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 a bottom corner of the pattern structure 3030. In the positive acoustic pressure operation of the ultrasonic wave or the megasonic wave shown in fig.3B, F1 is the ultrasonic wave or the megasonic wave pressure acting on the bubble 3050, F2 is the reaction force acting on the bubble 3050 generated by the substrate 3010 when the bubble 3050 is pressed against the substrate 3010, and F3 is the reaction force acting on the bubble 3050 generated by the side wall of the pattern structure 3030 when the bubble 3050 is pressed against the side wall of the pattern structure 3030. In the ultrasonic or megasonic negative sound pressure operation shown in fig.3C and 3D, the bubble 3050 expands and becomes large because the ultrasonic or megasonic negative force stretches the bubble 3050. During the expansion of the bubble volume, F1 ' is the force of bubble 3050 pushing cleaning solution 3070, F2 ' is the force of bubble 3050 pushing substrate 3010, and F3 ' is the force of bubble 3050 pushing the sidewall of patterned structure 3030. After the positive sound pressure and the negative sound pressure of the ultrasonic wave or the megasonic wave are alternately applied for several cycles, the gas temperature in the bubble becomes higher and the bubble volume becomes larger, and finally, the bubble implosion 3051 occurs, 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 sidewall of the pattern structure 3030, as shown in fig. 3G. The implosion force causes the sidewalls of the pattern structure 3030 to be damaged, as shown in fig. 3H.

In order to avoid damage to the pattern structure on the substrate due to implosion of bubbles during the wet cleaning using ultrasonic or megasonic assistance, it is preferable that the bubbles be separated from the surface of the pattern structure and the substrate before sonic energy is applied to the cleaning liquid to clean the substrate.

Various methods of separating bubbles from the patterned structure surface and the substrate are disclosed below.

Fig.4A and 4B disclose one embodiment of a substrate pretreatment to separate bubbles from the surface of a pattern structure on a substrate according to the present invention. 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 a bottom corner of the pattern structure 4030, as shown in fig. 4A. Therefore, before cleaning the substrate using ultrasonic waves or megasonic waves, a bubble separation pretreatment is required. In the bubble separation pretreatment process, a method such as increasing the surface wettability of the pattern structure 4030 from the solid surface direction D1 along the pattern structure 4030 and the solid surface direction D2 along the substrate 4010, respectively, or interfering from the directions D1 and D2 using a minimum mechanical force, 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 are gradually contracted for the purpose of separating the bubble from the surface of the pattern structure 4030 and the substrate 4010, as shown in fig. 4B.

An embodiment of the bubble separation pretreatment process according to the present invention is to change the surface of the substrate 4010 from hydrophobic to hydrophilic by providing a chemical solution on the surface of the substrate 4010, e.g. providing a chemical solution, forming a hydrophilic coating on the surface of the substrate 4010, or oxidizing a hydrophobic surface material such as silicon or polysilicon layer to a hydrophilic silicon oxide layer using a chemical solution such as ozone solution or SC1 solution (ammonium hydroxide, hydrogen peroxide, water mixture).

One embodiment of the bubble separation pretreatment process according to the present invention is to provide a chemical solution containing a surfactant, an additive or a chelating agent to the surface of the substrate 4010. The chemical solution containing a surfactant, an additive, or a chelating agent 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 group-containing ethylenediaminetetraacetic acid (EDTA), tetracarboxyldiaminopropionic acid (EDTP) acid/salt, etc. are doped in the chemical solution as a surfactant to improve wettability of the chemical solution.

In addition, low power ultrasonic waves or megasonic waves can be incorporated into the various embodiments described above to improve bubble separation efficiency. Low power ultrasonic or megasonic waves generate small mechanical forces that contribute to stable cavitation oscillations, thereby generating mechanical forces that separate bubbles 4050 from the surface of pattern structure 4030 and the surface of substrate 4010. The low power ultrasonic or megasonic waves can be operated in a continuous mode (non-pulsed mode) and the power density can be, for example, 1mw/cm²-15mw/cm². The duration of applying low power ultrasonic or megasonic waves with a continuous mode to the cleaning fluid to detach bubbles from the surface of the pattern structure 4030 and the surface of the substrate 4010 may be, for example, 10s to 60 s. PCT/CN2008/073471, filed 12/2008, discloses a more detailed description of the application of continuous mode ultrasonic or megasonic waves to a cleaning fluid, all of which are incorporated herein by reference. Low power ultrasonic or megasonic waves can be operated in a pulsed mode, and the power density can be, for example, 15mw/cm²-200mw/cm². The duration of applying low power ultrasonic or megasonic waves having a pulsed mode to the cleaning fluid to detach bubbles from the surface of the pattern structure 4030 and the surface of the substrate 4010 may be, for example, 10s to 120 s. PCT/CN2015/079342 filed 5/20/2015 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 fig.5A to 5C, an embodiment of the bubble separation pretreatment process according to the present invention is disclosed to remove impurities, such as metal impurities, organic contaminants, and polymer residues, attached to the surface of the substrate. The bubbles 5050 easily adhere around the impurities 5090 such as metal impurities, organic contaminants, and polymer residues on the surface of the substrate 5010, and thus the bubbles 5050 adhering to the pattern structures 5030 and the surface of the substrate 5010 run the risk of imploding and damaging the pattern structures 5030 on the substrate 5010 during the subsequent ultrasonic or megasonic cleaning. A pretreatment method for providing a chemical solution on the surface of the substrate 5010 helps to remove impurities 5090, such as metal impurities and polymer residues, on the surface of the substrate 5010 prior to ultrasonic or megasonic cleaning processes, for example, oxidizing the surface polymer residues with an ozone solution, or carbonizing the surface polymer residues with a high temperature (90-150 ℃) SPM solution (sulfuric acid, hydrogen peroxide mixture). In another embodiment, chemicals such as EDTA may also be used for surface metal ion chelation to remove metal impurities.

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

Referring to fig.6A to 6C, according to another embodiment of the present invention, in the pretreatment step, low power ultrasonic wave or megasonic wave process is used to improve the removal efficiency of the impurity 6090, such as the removal of organic pollutants using ozone solution or SC1 solution, as shown in fig. 6A. Due to the application of low power ultrasonic waves or megasonic waves, the volume of the bubble 6050 alternately expands and contracts, thereby causing the impurities 6090 to fully contact the chemical solution and further react with the chemical solution. This process accelerates the efficiency of the reaction of the chemical solution with impurity 6090. As the impurities 6090 are removed from the surface of the pattern structure 6030, the wettability of the chemical solution increases such that the bubbles 6050 leave the surface of the pattern structure 6030, as shown in fig. 6C. Low work powerThe rate ultrasound or megasonic waves can be operated in continuous mode (non-pulsed mode) and the power density can be, for example, 1mw/cm²-15mw/cm². Low power ultrasound or megasonic waves can also be operated in a pulsed mode, the power density may be, for example, 15mw/cm²-200mw/cm²。

Fig.7A and 7B disclose one embodiment of separating bubbles from the surface of a pattern structure on a substrate according to the present invention. If the particles 7090 become trapped in the corners of the patterned structure 7030 of the substrate 7010, the gas bubbles 7052, 7054, 7056 tend to collect more easily around the surface of the particles 7090 due to the irregular shape of the particles. The air bubbles 7052, 7054, 7056 attached to the surface of the pattern structure 7030 and the surface of the particles 7090 run the risk of implosing and damaging the pattern structure 7030. Therefore, a particle removal and bubble separation pretreatment process is required before the ultrasonic or megasonic cleaning process is performed.

As shown in fig.7A and 7B, in the pretreatment process, the particles 7090 are removed to further separate the bubbles 7052, 7054, 7056 from the surface of the pattern structure 7030 and the surface of the substrate 7010. Prior to the ultrasonic or megasonic cleaning process, low power ultrasonic or megasonic waves may be applied to the cleaning fluid 7070 to remove the particles 7090 and to detach the bubbles 7052, 7054, 7056 from the surface of the pattern structure 7030 and the surface of the substrate 7010. Low power ultrasonic or megasonic waves create cavitation oscillations on the bubbles 7052, 7054, 7056. The mechanical forces F1, F2, F3 and the resultant force F from the cavitation oscillations of the bubbles 7052, 7054, 7056 push the particles 7090 outward, as shown in fig. 7A. The particles 7090 are eventually pushed upward, and the cavitation oscillating forces of the bubbles 7052, 7054, 7056 also produce acoustic agitation that separates the bubbles 7052, 7054, 7056 from the surface of the patterned structure 7030 and the surface of the substrate 7010. Low power ultrasound or megasonic waves can be operated in continuous mode (non-pulsed mode), and the power density can be, for example, 1mw/cm²-15mw/cm². Low power ultrasonic or megasonic waves can also be operated in a pulsed mode, the power density may be, for example, 15mw/cm²-200mw/cm²。

Fig.8A and 8B disclose 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, 8056 from the surface of the pattern structure 8030 and the surface of the substrate 8010. The chemical solution may be an ozone solution or a SC1 solution, oxidizing the polymer particles. In this process, a low power ultrasonic or megasonic process may also be used to assist the chemical reaction or dissolution prior to a subsequent ultrasonic or megasonic cleaning process. Low power ultrasonic or megasonic waves create cavitation oscillations on the bubbles 8052, 8054, 8056 around the particles 8090 trapped in the corners of the patterned structure 8030. The mechanical forces F1, F2, F3 and the resultant force F generated by the cavitation oscillations of the bubbles 8052, 8054, 8056 push the particles 8090 outward. The chemical solution reacts or dissolves the particles 8090 and the resultant mechanical force of the low power ultrasonic or megasonic waves causes the particles 8090 to eventually be pushed upward. The cavitation oscillating force of the bubbles 8052, 8054, 8056 also generates acoustic agitation to separate the bubbles 8052, 8054, 8056 from the surface of the pattern structure 8030 and the surface of the substrate 8010.

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

placing a substrate on a substrate holding device;

conveying a cleaning solution to the surface of the substrate;

performing a pre-treatment process to separate bubbles from the substrate surface; and

an ultrasonic or megasonic cleaning process is performed to clean the substrate.

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

Fig.9 discloses one embodiment of a substrate cleaning method according to the present invention. In this embodiment, ultrasonic or megasonic waves operating in a pulsed mode are applied in the pretreatment process to detach bubbles from the substrate surface. The ultrasonic or megasonic waves have a first power, which may be, for example, 15mw/cm²-200mw/cm². The duration of the separation of bubbles using pulsed mode low power ultrasound or megasonic waves may be, for example, 10s to 120 s. After separation of the bubbles from the substrate surface, subsequently, in pulsed modeThe down-running ultrasonic or megasonic waves are applied to perform an ultrasonic or megasonic cleaning process to clean the substrate. The ultrasonic or megasonic waves have a second power, which is higher than the first power, and the power density of the second power may be, for example, 0.2w/cm²-2w/cm². The duration of cleaning the substrate using pulsed mode high power ultrasound or megasonic may be, for example, within 600 s.

Fig.10 discloses 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 detach bubbles from the substrate surface. The ultrasonic or megasonic waves have a first power, which may be, for example, 1mw/cm²-15mw/cm². The duration of the separation of bubbles using continuous mode low power ultrasound or megasonic waves may be, for example, 10s to 60 s. After the bubbles are detached from the substrate surface, ultrasonic or megasonic waves operating in a pulsed mode are then applied to perform an ultrasonic or megasonic cleaning process to clean the substrate. The ultrasonic or megasonic waves have a second power, which is higher than the first power, and the power density of the second power may be, for example, 0.2w/cm²-2w/cm². The duration of cleaning the substrate using pulsed mode high power ultrasound or megasonic may be, for example, within 600 s.

Fig.11 discloses yet another embodiment of a substrate cleaning method according to the present invention. In this embodiment, ultrasonic or megasonic waves operating in a pulsed mode are applied in the pretreatment process to detach bubbles from the substrate surface. The ultrasonic or megasonic waves have a first power, which may be, for example, 15mw/cm²-200mw/cm². The duration of the separation of bubbles using pulsed mode low power ultrasound or megasonic waves may be, for example, 10s to 120 s. After the bubbles are detached from the substrate surface, ultrasonic or megasonic waves operating in a continuous mode (non-pulsed mode) are then applied to perform an ultrasonic or megasonic cleaning process to clean the substrate. The ultrasonic or megasonic waves have a second power, the second power being higher than the first power, the power density of the second power may be,e.g. 15mw/cm²-500mw/cm². The duration t2 for cleaning the substrate using continuous mode high power ultrasonic or megasonic waves may be, for example, 10s-60 s. At time t2, bubble implosion or unstable cavitation oscillation may occur, however, since it occurs above the structure, the impact force generated by the microjet may not damage the pattern structure on the substrate.

Fig.12 discloses yet 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 in the pretreatment process to detach bubbles from the substrate surface. The ultrasonic or megasonic waves have a first power, which may be, for example, 1mw/cm²-15mw/cm². The duration of the separation of bubbles using continuous mode low power ultrasound or megasonic waves may be, for example, 5s to 60 s. After the bubbles are detached from the substrate surface, ultrasonic or megasonic waves operating in a continuous mode (non-pulsed mode) are then applied to perform an ultrasonic or megasonic cleaning process to clean the substrate. The ultrasonic or megasonic waves have a second power, which is higher than the first power, and the power density of the second power may be, for example, 15mw/cm²-500mw/cm². The duration of cleaning the substrate using the continuous mode high power ultrasonic wave or megasonic wave may be, for example, 10s to 120 s.

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

Referring to fig.13A and 13B, one embodiment of a substrate cleaning apparatus according to the present invention is disclosed. Fig.13A is a sectional view of the substrate cleaning apparatus, which includes: a substrate holding device 1314 for holding a substrate 1310, a spin drive module 1316 driving the substrate holding device 1314, and a showerhead 1312 for delivering cleaning fluids and chemical solutions 1370 to the surface of the substrate 1310. The substrate cleaning apparatus also includes an ultrasonic or megasonic device 1303 positioned over the substrate 1310. The ultrasonic or megasonic device 1303 further includes a piezoelectric transducer 1304 and an acoustic resonator 1308 paired therewith. Upon energization of the piezoelectric transducer 1304, which acts as a vibration, the acoustic resonator 1308 transmits low or high acoustic energy into the cleaning solution or chemical solution. Cavitation oscillations of the bubbles produced by the low acoustic energy cause the bubbles to detach from the surface of the substrate 1310. Cavitation oscillations of bubbles generated by the high acoustic energy vibrate contaminants, such as foreign particles, on the surface of the substrate 1310 loose.

Referring again to fig.13A, the substrate cleaning apparatus further includes an arm 1307 connected to the ultrasonic or megasonic device 1303, the arm 1307 being used to move the ultrasonic or megasonic device 1303 in the vertical direction Z to vary the liquid film thickness d. Vertical drive module 1306 drives arm 1307 to move vertically. The vertical drive module 1306 and the rotational drive module 1316 are both controlled by a controller 1388.

Fig.13B is a top view of the substrate cleaning apparatus shown in fig. 13A. The ultrasonic or megasonic device 1303 covers only a small area of the substrate 1310, and thus requires rotation to achieve uniform sonic energy across the entire substrate 1310. Although only one ultrasonic or megasonic device 1303 is shown in fig.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 fluids or chemical solutions to the surface of the substrate 1310.

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

In summary, the present invention has been described in detail with reference to the above embodiments and the accompanying drawings, so that those skilled in the art can implement the invention. The above-described embodiments are intended to be illustrative, but not limiting, of the present invention, the scope of which is defined by the appended claims. Variations on the number of elements described herein or substitutions of equivalent elements are intended to be within the scope of the present invention.