Apparatus and method for cleaning

A semiconductor structure includes a molding compound, a conductive plug, and a cover. The conductive plug is in the molding compound. The cover is over a top meeting joint between the conductive plug and the molding compound. The semiconductor structure further has a dielectric. The dielectric is on the cover and the molding compound.

FIELD

The disclosure relates to an apparatus and a method for cleaning a plate, and more particularly to a cleaning system for cleaning a plate designed for cleaning a wafer surface.

BACKGROUND

Wafer level packaging (WLP) technology combines dies having different functionalities at a wafer level, and is widely applied in order to meet continuous demands toward the miniaturization and higher functions of electronic components. The WLP technology includes few operations, such as bonding two different wafers into an integral part (called wafer bonding hereinafter) and then proceeding to a sigulation process to cut the integral part into a singulated package.

Fusion bonds and hybrid bonds are two terms generally used to categorize various wafer bonding methods. A fusion bond refers to a wafer bonding method in which there is only dielectric material involved on the bonding surface. The hybrid bond, on the other hand, refers a wafer bonding method in which has a dielectric and a metallic material contained on the bonding surface. The hybrid bond is more complicated than the fusion bond because it includes two different materials. In some examples such as CMOS image sensor (CIS) wafer bonding, a bonded interface includes copper and silicon oxide.

The wafer bonding is based on chemical bonds between two surfaces of any materials that meet numerous requirements specified for the wafer surface. As such, the wafer surface must be clean. Otherwise, unbonded areas called voids, i.e. interface bubbles, can occur. However, during a wafer bonding process, cleanness of a wafer surface is a challenge and affected by some factors, such as cross contamination or clean tool deviation. Thus, a system or a method to provide a clean wafer surface is still in great demand.

DETAILED DESCRIPTION OF THE INVENTION

In the present disclosure, an apparatus is designed to clean a plate that is used to clean a surface of a wafer. The plate is constantly cleaned with the apparatus in order to keep the plate in an optimized condition, such as without any particle or other contamination sources attached.

In various embodiments, the plate and the apparatus are in a system and the system is used to clean a surface of a wafer before the wafer is bonded to another wafer. In some embodiments, the plate in system is designed to clean a batch of wafers continuously and the apparatus built in the system is designed to clean the plate with a predetermined interval. Thus, the plate does not cause the cross contamination on the wafers.

FIG. 1is a semiconductor wafer cleaning system200designed to clean a top surface1of a semiconductor wafer2. In various embodiments, the semiconductor wafer2includes CIS devices and the top surface1includes oxide and metal. In some embodiments, the metal includes copper. The semiconductor wafer2is directly bonded with another wafer after cleaned by the semiconductor wafer cleaning system200. In some embodiments, the semiconductor wafer cleaning system200is connected with a loader3and the loader3is designed to send wafers continuously into the semiconductor wafer cleaning system200. In some embodiments as inFIG. 1, the semiconductor wafer cleaning system200has several chambers, such as4and5and the semiconductor wafer2travels through the chambers4and5to receive a complete clean operation. A first chamber4is a wafer clean station in which the top surface1of the semiconductor wafer2is cleaned when the semiconductor wafer2is located inside the first chamber4. In addition, semiconductor wafer cleaning system200includes a cup6, a clean unit50, a plate22and an arm21connecting to the plate22in the first chamber4. A wafer chuck7is inside the cup6and a container51is disposed inside the clean unit50.

The first chamber4includes the cup6designed for accommodating the semiconductor wafer2and draining a clean liquid, which is used to clean the semiconductor wafer2. The wafer chuck7is designed for holding the semiconductor wafer2on the wafer chuck7for further spinning motion. In some embodiments, the wafer chuck7applies vacuum to the bottom surface of the semiconductor wafer2so as to hold the semiconductor wafer2on the wafer chuck7in a rotation (from about 500 to about 5000 rpm). In addition, the second chamber5is designed for other wafer processes, such as drying wafer bonding and so on.

The plate22is used to clean the top surface1of the semiconductor wafer2. In some embodiments, the semiconductor wafer cleaning system200is designed to be able to operate under a first mode and a second mode. Under the first mode, the plate22is at a first position8. Under the second mode, the plate22is at a second position9. In some embodiments, the first mode is a run mode, which indicates that the semiconductor wafer2is in the first chamber4and cleaned by the plate22. The second mode is a self-clean mode, which indicates that the plate22is cleaned in a clean unit50.

The arm21designed to control the position of the plate22, which is pivoted to an arm21. In some embodiments, the arm21conducts a three-dimensional motion.FIG. 2is an enlarged view of the arm21and the plate22. The arm21moves the plate22along X, Y, or Z direction. In some embodiments, the plate22is swiveled by the arm21, for example the plate22is moved from the first position8to the second position9as previously discussed with reference toFIG. 1.

In some embodiments as inFIG. 2, the plate22is in a pie shape that is designed for cleaning a great amount of the wafer surface per timeframe. However, in certain embodiments, the plate22is in, but not limited to, a triangular shape, a square shape, a quadrilateral shape, or a polygonal shape. Other shapes are within the contemplated scope of the present disclosure.

FIG. 3is a cross-sectional view of a plate22. The plate22includes a first layer221and a second layer222. The first layer221includes several holes223as liquid inlets. In some embodiments, the holes223are connected with tubes for introducing clean liquid into the plate22. The second layer222includes several through holes224guiding the clean liquid from the hole223to the top surface1of the semiconductor wafer2as previously discussed with reference toFIG. 1.

In some embodiments as inFIG. 4, the first layer221includes a first hole225and a second hole226. The first hole225is designed for the clean liquid to flow in and the second hole226is configured to drain the clean liquid out so as to clean a top surface of a semiconductor wafer.

In some embodiments as inFIG. 5, the second layer222includes several pores227. In certain embodiments, some of the pores227are connected with each other. The pores227are channels to guide the clean liquid from holes223to a top surface of a semiconductor wafer. In certain embodiments, the pores227are designed to form inside the plate22or on a surface of the second layer222.

In some embodiments, the plate22includes the second layer222without the first layer211disposed thereon. In some embodiments, a pipe is configured to directly guide the clean liquid to the through holes224or to the pores227as previously discussed with references toFIGS. 3 to 5.

FIG. 6is a portion of a semiconductor wafer cleaning system200aaccording to some embodiments of the present disclosure. A sonicator30is coupled to the plate22as previously discussed and the plate22is located in the container51of the clean unit50. A wire31is designed to transfer a signal S between the sonicator30and a second layer222of the plate22. The semiconductor wafer cleaning system200aincludes a wave sensor24coupled to the plate22. An electric wire25is designed to transfer a reflected signal between the wave sensor24and the second layer222of the plate22. The arm21is connected to the plate22.

The sonicator30is designed to generate the signal S toward the plate22. In some embodiments, the signal S has a frequency from about 20 KHz to about 40 KHz. In some other embodiments, the frequency is from about 25 KHz to about 60 KHz. In still other embodiments, the frequency is from about 28 KHz to about 80 KHz. In various embodiments, the second layer222is activated by the signal S so as to sonicate a liquid in the second layer222. The previously discussed frequency is used to properly sonicate the liquid. In some embodiments, the sonicator30is inside the second layer222such that the sonicator30transfers the signal S without the wire31. In some embodiments, the sonicator30is inside the arm21and the sonicator30is controlled correspondingly to the position of the plate22. Once the arm21is located at a prearranged position, the sonicator30transfers the signal S to the plate22. In some other embodiments, the signal S from the sonicator30is wirelessly transferred to the plate22.

The signal S has a power for generating an ultrasonic wave. In some embodiments, the power of the ultrasonic wave generated by the sonicator30is adjustable. In some embodiments, the power is in a range from about 19 to about 35 W. In some other embodiments, the power is in a range from about 15 to about 23 W. In some other embodiments, the power is in a range from about 18 to about 33 W. In certain embodiments, the power is manually adjusted to the previously discussed ranges to avoid cross contamination. In some other embodiments, the power is automatically adjusted to the previously discussed ranges to prevent the power of the signal S from over 35 W. Once the power is over 35 W, the cross contamination effect occurs frequently.

The wire31is electrically connected between the sonicator30and the plate22. In certain embodiments, the wire31is inside the arm21to prevent the wire31from contacting the liquid. In certain embodiments, the wire31is connected with the first layer221in order to be coupled with the second layer222so as to transfer the signal S to the second layer222.

The plate22is used to generate the ultrasonic wave. Because the second layer222of the plate22includes a piezoelectric material, the signal S used to agitate the second layer222so as to generate the ultrasonic wave. In some embodiments, the first layer221includes a piezoelectric material, which is agitated by the signal S to generate the ultrasonic wave.

In some embodiments, the plate22is used to receive a reflected ultrasonic wave from a bottom surface55of the clean unit50. The second layer222of the plate22converts the reflected ultrasonic wave to a reflected signal R and transfers the reflected signal R to the wave sensor24. In other words, the piezoelectric material of the second layer222of the plate22converts the reflected ultrasonic wave from the bottom surface55of the container51to the reflected signal R. In certain embodiments, the piezoelectric material of the first layer221converts the reflected ultrasonic wave to the reflected signal R, which is transferred to the wave sensor24.

The electric wire25is electrically connected between the plate22and the wave sensor24. In some embodiments, the electric wire25is inside the arm21to prevent the electric wire25from contacting the liquid. In certain embodiments, the electric wire25is connected with the first layer221in order to be coupled with the second layer222so as to transfer the reflected signal R to the wave sensor24.

In various embodiments, the wave sensor24is used to calibrate the power of the ultrasonic wave generated by the sonicator30. In some embodiments, the wave sensor24calculates a reflected power corresponding to the reflected signal R. The reflected power calculated is used to check up the power of the ultrasonic wave generated by the sonicator30. In some embodiments, the wave sensor24transfers the reflected signal R to a processor. The processor calculates the reflected power corresponding to the reflected signal R. The reflected power calculated is used to check up the power of the ultrasonic wave generated by the sonicator30.

In certain embodiments, the wave sensor24is disposed on the plate22. In some embodiments, the wave sensor24is inside the second layer222. In some other embodiments, the wave sensor24is inside the arm21to prevent the wave sensor24from contacting the liquid.

In some embodiments, the wave sensor24transfers an adjusting signal to the sonicator30. The power of the ultrasonic wave generated by the sonicator30is adjusted in accordance with the adjusting signal so as to fall into the previously discussed ranges. In certain embodiments, the second layer222of the plate22includes a wireless transmitter, which transfers the reflected signal R to the wave sensor24. Additionally, the wave sensor24includes a wireless module that transfers the adjusting signal to the sonicator30. In some other embodiments, the wave sensor24is used to judge whether the power of the ultrasonic wave falls within the power range as previously discussed. If not, the sonicator30is adjusted until the power of the ultrasonic wave falls within the range. Thus, the wave sensor24is designed to prevent the power of the ultrasonic wave from exceeding 35 W so as to avoid the cross contamination.

InFIG. 6, the clean unit50of the semiconductor wafer cleaning system200ais configured to receive the plate22during the second mode. The clean unit50includes the container51used for accommodating the liquid. Moreover, the container51includes an opening52which allows the arm21to pivot the plate22through the opening52. In some embodiments, the opening52is used for the liquid to pour into the container51.

In some embodiments as referred inFIG. 7, the plate22, the arm21, the wave sensor24, the sonicator30, the wire31, and the electric wire25are previously discussed with reference toFIG. 6. The clean unit50includes a wave reflector54that is disposed on the bottom surface55of the container51. That is, the wave reflector54is disposed under the plate22and designed to reflect the ultrasonic wave from the second layer222of the plate22during the second mode for adjusting the power of the ultrasonic wave.

In other embodiments, the wave reflector54is disposed between the plate22and the container51. In other words, the wave reflector54is disposed above the bottom surface55of the container51

In order for the precise adjustment of the ultrasonic power, the gap D between the wave reflector54and a surface228of the plate22is a predetermined distance. In some embodiments, the predetermined gap D is between about 1 mm and about 4 mm. In certain embodiments, the predetermined gap D is between about 0.5 mm and about 2.8 mm. In other embodiments, the predetermined gap D is between about 1.7 mm and about 3.1 mm. In some other embodiments, the predetermined gap D is between about 1.3 mm and about 4.6 mm. The previous gap distance is designed to eliminate the deviation of the power of the ultrasonic wave to avoid cross contamination.

FIG. 8is a portion of a semiconductor wafer cleaning system200baccording to some embodiments of the present disclosure. The plate22and the arm21are previously discussed with reference toFIG. 6. The semiconductor wafer cleaning system200bincludes a particle removal component10designed for cleaning the plate22. For instance, the particle removal component10utilizes, but not limited to, a stream of flow to detach the particles trapped inside the second layer222of the plate22.

In some embodiments as referred inFIG. 8, the particle removal component10includes an exit11. The exit11is disposed at a wall56of the container51and designed to drain the liquid out so as to form a stream of flow. The stream of flow detaches the particle and carries the particle out of the container51. Thus, the plate22is cleaned by the particle removal component10.

FIG. 9is a portion of a semiconductor wafer cleaning system200caccording to some embodiments of the present disclosure. The particle removal component10includes a moving arm12and a cleaning bar13, which is pivoted to the moving arm12. The cleaning bar13includes several protrusions131that are used to scrub the plate22. Mechanical cleaning force is applied to the plate22and the particles are removed from the plate22.

FIG. 10is a portion of a semiconductor wafer cleaning system200daccording to some embodiments of the present disclosure. The plate22, the arm21, and the container51are previously discussed with reference toFIG. 6. The particle removal component10includes a tube14and a nozzle15, which is connected to the tube14. The tube14is designed to guide the liquid to the nozzle15and the nozzle15is used to eject the liquid to the plate22for cleaning.

FIG. 11is a semiconductor wafer cleaning system200eaccording to some embodiments of the present disclosure. The top surface1, the semiconductor wafer2, the loader3, the chambers4and5, the cup6, the wafer chuck7, the clean unit50, the container51, the arm21and the plate22are previously discussed with reference toFIG. 1. The semiconductor wafer cleaning system200efurther includes an IPA tank57. The semiconductor wafer cleaning system200eis designed to be able to operate under a third mode. Under the third mode, the plate22is located at a position58. In some embodiments, the third mode is a dry mode, which indicates that the plate22is dried in the IPA tank57.

FIG. 12is an enlarged view of the IPA tank57designed for dehydrating the plate22. The IPA tank57is used to accommodate the non-polar solvent for dehydrating the plate22. In certain embodiments, the IPA tank57is replaced by a heating element, which dries the plate22during the third mode. Thus, the plate22is heated by the heating element.

FIG. 13is an apparatus70used for cleaning a plate22designed for cleaning a wafer surface. The apparatus70includes a container51, an exit11and a sonicator30as previously discussed. However, the sonicator30is coupled to the container51for generating an ultrasonic wave.

In some embodiments, the exit11is located at the wall56of the container51. However, in certain embodiments, the exit11is disposed at the bottom surface55of the container51.

In some embodiments, the sonicator30coupled to the container51generates a signal U toward the container51. In some embodiments, the signal has a frequency from about 19 KHz to about 39 KHz. In other embodiments, the frequency is from about 26 KHz to about 61 KHz. In still other embodiments, the frequency is from about 29 KHz to about 79 KHz. The previously discussed frequency is used to properly agitate the liquid. In certain embodiments, the container51is agitated by the signal U so as to sonicate the liquid in the container51and to generate an ultrasonic wave.

In some embodiments, the power of the ultrasonic wave from the sonicator30is adjustable. In some embodiments, the ultrasonic power is adjustable in a range from about 18 to about 35 W. In other embodiments, the power is in a range from about 14 to about 22 W. In some other embodiment, the power is in a range from about 17 to about 34 W.

FIG. 14is an apparatus70aaccording to some embodiments of the present disclosure. The sonicator30is coupled to the plate22and the container51. In addition, the container51includes the wave reflector54which is protruded from the bottom surface55of the container51. The wave reflector54is disposed parallel to the second layer222of the plate22for a complete wave reflection without deviation. Furthermore, because the sonicator30is coupled to the plate22and the container51, the plate22and the container51are simultaneously agitated and oscillate with greater amplitude at some frequencies so as to form the ultrasonic wave. The frequency is from about 29 KHz to about 35 KHz. In some other embodiments, the frequency is from about 31 KHz to about 58 KHz. In still other embodiments, the frequency is from about 37 KHz to about 67 KHz. In addition, the exit11is used to form the stream of flow, which is able to carry the particles, detached by the ultrasonic wave, out of the container51.

FIG. 15is an apparatus70baccording to some embodiments of the present disclosure. The apparatus70bfurther includes an inlet59, which is disposed on a first side53of the container51. The first side53is disposed corresponding to the wall56. In other words, the inlet59is disposed relative to the exit11. The inlet59and the exit11are designed to form a stream of flow. The inlet59and the exit11to form a turbulence of flow toward the plate22for cleaning the plate22.

FIG. 16is an apparatus70caccording to some embodiments of the present disclosure. The apparatus70cincludes a particle removal component10. The particle removal component10has a brush16including a brush arm161and a brush head162connected with the brush arm161. The brush head162is pivoted on the brush arm161. The brush arm161is designed to move along X, or Z direction. In certain embodiments, the brush head162is swiveled by the brush arm161for cleaning the second layer222of the plate22. In other words, the brush16is designed to travel in a lower portion17of the container51.

FIG. 17is an apparatus70daccording to some embodiments of the present disclosure. The apparatus70dincludes a heating element18, which is used to dehydrate the plate22in the third mode. In certain embodiments, the heating element18is an IR lamp, which dehydrates the plate22by irradiation. In some other embodiments, the heating element18is an electric heating device, which blows hot air to dry the plate22.

FIG. 18is an apparatus70eaccording to some embodiments of the present disclosure. The container51ais in a conical shape. The exit11is disposed at the bottom of the container51a. The apparatus70eincludes an electric dipole19which is disposed at the bottom surface55aof the container51a. The electric dipole19is designed for detaching the particles from the second layer222of the plate22through electric attraction force. In certain embodiments, the electric dipole19is disposed adjacent to the plate22during a predetermined mode for maximizing the electric attraction force between the electric dipole19and particles in the plate22. In some other embodiments, the electric dipole19is disposed between the plate22and the container51as previously discussed to detach the particles.

FIG. 19is an apparatus70faccording to some embodiments of the present disclosure. The apparatus70fhas a container51bincluding a first wall511and a second wall512. The height of the second wall512is higher than the height of the first wall511. The second wall512surrounds the first wall511. The inlet59is disposed at the bottom of the first wall511while the exit11is disposed around the inlet59. Because the sonicator30is coupled to the first wall511, the first wall511is agitated to form the ultrasonic wave. The inlet59is disposed under the plate22and form a flow to detach the particles trapped into the plate22.

FIG. 20is an apparatus70gaccording to some embodiments of the present disclosure. The apparatus70gincludes a nozzle15a, which is connected with the inlet59. In other words, the nozzle15ais in the container51b. The nozzle15ais used to from a turbulence of flow toward the second layer222of the plate22and to detach the particles from the plate22.

A method of cleaning a plate designed to clean a wafer surface is through a stream of flow, a turbulence of flow, a mechanical cleaning force or a combination thereof. The method includes a number of operations and the description and illustration are not deemed as a limitation as the order of the operations.

A term “moving” or “moved” is used in the present disclosure to describe an operation of locating an object to a specific site. The moving operation includes various steps and processes and varies in accordance with the features of embodiments. In some embodiments, a moving operation includes locating a plate to a container, a tank or a cup. In certain embodiments, a moving operation includes locating a plate to a position during a specific mode.

A term “immersing” or “immersed” is used in the present disclosure to describe an operation of covering an object with a liquid. The liquid is a hydrophilic solvent or a hydrophobic solvent. The immersing operation includes various steps and processes and varies in accordance with the features of embodiments. In some embodiments, an immersing operation includes covering a portion of the object. For instance, immersing the plate indicates immersing the second layer instead of the first layer, which is disposed on the second layer.

A term “applying” or “applied” is used in the present disclosure to describe an operation of enforcing a power on an object or an intermediate. The applying operation includes various steps and processes and varies in accordance with the features of embodiments. In some embodiments, the applying operation includes agitating the liquid to form the ultrasonic wave which is transferred toward the plate.

A term “dehydrating” or “dehydrated” is used in the present disclosure to describe an operation of taking moisture out of an object. The dehydrating operation includes various steps and processes and varies in accordance with the features of embodiments. In some embodiments, the dehydrating operation includes drying out the plate. In certain embodiments, the dehydrating operation includes heating the plate to remove the moisture.

A term “sensing” or “sensed” is used in the present disclosure to describe an operation of receiving the reflected ultrasonic wave. The sensing operation includes various steps and processes and varies in accordance with the features of embodiments. In some embodiments, the sensing operation includes receiving the reflected ultrasonic wave from the container. In certain embodiments, the sensing operation includes receiving the reflected ultrasonic wave from the wave reflector.

A term “swiveling” or “swiveled” is used in the present disclosure to describe an operation of rotating an object corresponding to the container. The swiveling operation includes various steps and processes and varies in accordance with the features of embodiments. In some embodiments, the swiveling operation includes rotating the plate parallel to the bottom surface of the container.

A term “scrubbing” or “scrubbed” is used in the present disclosure to describe an operation of cleaning an object with gentle rubbing. The scrubbing operation includes various steps and processes and varies in accordance with the features of embodiments. In some embodiments, the scrubbing operation includes rubbing a surface of the plate.

FIG. 21is a diagram of a method300for cleaning a plate designed for cleaning a wafer surface, according to some embodiments of the present disclosure. The method300includes several operations, which are discussed in detail with reference toFIGS. 22 to 26. At operation302, the plate22is moved to a container51. At operation304, the plate22is immersed into a liquid40. At operation306, a power of an ultrasonic wave is applied on the plate22. At operation308, the plate22is dehydrated.

InFIG. 22, the loader3of the semiconductor wafer cleaning system200epasses the semiconductor wafer2to the cup6and the wafer chuck7holds the semiconductor wafer2in the chamber4. The arm21moves the plate22to position8to clean the top surface1of the wafer2in the first mode. After the first mode, the plate22is moved to position9so as to perform the second mode. In the second mode, the plate22is cleaned in the container51of the clean unit50. At position9, the particles trapped in the plate22are detached by the particle removal component. Finally, the plate22is moved from position9to position58, where the plate22is located in the IPA tank57and dehydrated in the third mode.

In some embodiments, the semiconductor wafer cleaning system200edrives the arm21to pivot the plate22above a semiconductor wafer2in the first mode. The power of the ultrasonic wave is applied to the plate22, which generates ultrasonic waves working as brushes for cleaning the top surface1.

FIG. 23is corresponding to the operation302inFIG. 21. In the second mode as inFIG. 23, the semiconductor wafer cleaning system200eoperates the arm21to place the plate22in the container51of the clean unit50. The plate22is disposed parallel to the bottom surface55of the container51. The wave sensor24is coupled to the plate22through the electric wire25. The sonicator30is coupled to the plate22through the wire31. Thus, the wire31and the electric wire25are placed into the container51after the operation302is performed.

FIG. 24is corresponding to the operation304inFIG. 21. The plate22is immersed into the liquid40. The liquid40flows into the container51through the opening52. The liquid40is, but not limited, selected from a citric acid solution, a formic acid solution and an ammonia solution. The percentage of citric acid in the citric acid solution by mass is, but not limited, from about 0.2% to about 2%. In some embodiments, the percentage thereof is from about 0.1% to about 1.8%. In some other embodiments, the percentage thereof is from about 0.5% to about 2.1%. In addition, the percentage of ammonia in the ammonia solution by mass is, but not limited, from about 0.4% to about 4%. In some other embodiments, the percentage thereof is from about 0.9% to about 1.8%. In certain embodiments, the percentage thereof is from about 2.1% to about 3.5%.

In some embodiments, swiveling the second layer222along X or Y direction in the container51agitates the turbulence of the liquid40around the plate22so as to efficiently clean the plate22. In certain embodiments, an operation of scrubbing the surface of the plate22by the mechanical cleaning force is performed to clean the plate22in the liquid40, which is used to carry the particles from the plate22.

FIG. 25is corresponding to the operation306inFIG. 21that a power P of an ultrasonic wave W is applied on the plate22. In some embodiments, the sonicator30applies the power P to the plate22. Because the second layer222includes piezoelectric material, the power P is converted into a physical vibration, which causes the liquid40to generate the ultrasonic wave W around the second layer222. The ultrasonic power is used to detach the particle60from the second layer222.

In some embodiments, the ultrasonic wave W is reflected from the bottom surface55so as to form a reflected ultrasonic wave RW. The second layer222senses the reflected ultrasonic wave RW and generates the reflected signal R. In other words, the method300includes an operation of sensing a reflected ultrasonic wave RW, which is reflected from the container51.

FIG. 26is corresponding to the operation308inFIG. 21. The plate22is immersed into the isopropyl alcohol71so as to remove the water molecule attached to the plate22.

In some embodiments, the IPA tank57is filled with a non-polar solvent selected from pentane, hexane, cyclohexane, benzene, toluene, chloroform, and diethyl ether. The non-polar solvent is used to replace the wafer molecule around the plate22and easily evaporates when the plate22is disposed above the non-polar solvent. In some other embodiments, the dehydrating operation308is implemented in the container51. The container51accommodates the non-polar solvent selected from isopropyl alcohol, pentane, hexane, cyclohexane, benzene, toluene, chloroform, and diethyl ether. The non-polar solvent is able to generate the ultrasonic wave or the stream of flow for cleaning the plate22and to dehydrate the plate22at the same time.

In some embodiments, an apparatus for cleaning a plate designed for cleaning a wafer surface includes a container, an exit, and a sonicator. The container includes an opening and a bottom surface. The opening is configured to receive the plate and the bottom surface, which is under the plate during a predetermined mode. The exit is disposed in the container. The sonicator is coupled to the container and applies an ultrasonic wave on the plate during the predetermined mode.

In some embodiments, a semiconductor wafer cleaning system includes a plate, an arm, a sonicator and a clean unit. The plate is configured to clean a wafer during a run mode. The arm is pivoted to the plate and controls the position of the plate. The sonicator is coupled to the plate. The clean unit is configured to receive the plate during a self-clean mode.

In some embodiments, a method for cleaning a plate designed for cleaning a wafer surface includes moving the plate to a container. The method also includes immersing the plate into a liquid. The method also includes applying a power of an ultrasonic wave on the plate. The method also includes dehydrating the plate.

Various operations of embodiments are provided herein. The order in which some or all of the operations are described should not be construed as to imply that these operations are necessarily order dependent. Alternative ordering will be appreciated by one skilled in the art having the benefit of this description. Further, it will be understood that not all operations are necessarily present in each embodiment provided herein. It will be appreciated that layers, features, elements, etc. depicted herein are illustrated with particular dimensions relative to one another, such as structural dimensions or orientations, for example, for purposes of simplicity and ease of understanding and that actual dimensions of the same differ substantially from that illustrated herein, in some embodiments.

Further, unless specified otherwise, “first,” “second,” or the like are not intended to imply a temporal aspect, a spatial aspect, an ordering, etc. Rather, such terms are merely used as identifiers, names, etc. for features, elements, items, etc. For example, a first channel and a second channel generally correspond to channel A and channel B or two different or two identical channels or the same channel.

As used in this application, “or” is intended to mean an inclusive “or” rather than an exclusive “or”. In addition, “a” and “an” as used in this application are generally to be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Furthermore, to the extent that “includes”, “having”, “has”, “with”, or variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to “comprising”.