Patent Description:
Workpieces used in the semiconductor industry, such as processing chamber components and the like, often require frequent cleaning in order to remove particles and otherwise unwanted material from the workpieces. For example, workpieces can be contaminated during deposition of thin films on a substrate in a processing chamber. For example, contaminants can fall onto substrates being processed in the processing chamber, and can cause defects in the eventual devices formed during the substrate processing.

Sonic cleaning systems include tanks for cleaning such workpieces are filled with a liquid. High frequency sound waves are generated via a transducer and propagate through the liquid to a workpiece located in the tank. The sound waves cause cavitation proximate the workpiece, which releases particles, such as dirt and grease, from the workpiece. Document <CIT> describes a method for pickling steel plates and a pickling device. In some embodiments, a cylindrical reflecting plate which surrounds the object being cleaned is used. Document <CIT> describes a cleaning system having a liner disposed within an outer basin. Multiple ultrasonic transducers may be used. Additional or alternative transducers may be placed in a vertical orientation along the side of the liner. The transducer may be positioned inside the liner or outside of the liner for indirect ultrasonication.

Document <CIT> discloses a cleaning system in accordance with the preamble of claim <NUM>. It describes a storage unit containing an object to be cleaned and located on a placement platform containing an ultrasonic oscillator.

One drawback with sonic cleaning systems in the art is that sonic waves are not properly focused on the workpieces during cleaning. In traditional sonic cleaning systems, ultrasonic and/or megasonic waves generated by the transducer are attenuated by corners of the tank in which the transducer is located. For example, the corners of the tanks disperse or otherwise attenuate the ultrasonic and/or megasonic waves generated by the ultrasonic transducers. In addition, traditional sonic cleaning systems have tanks that are much larger than workpieces located therein. In these tanks, the ultrasonic and/or megasonic waves are dispersed through the large tanks and are not sufficiently focused on the workpieces. Accordingly, the energy generated by the ultrasonic transducers in traditional sonic cleaning systems are not efficiently delivered to the workpiece and sonic cleaning is inefficient.

Therefore, what is needed in the art is apparatuses and methods with improved focus of sonic waves on workpieces.

Embodiments herein include apparatuses and methods for sonic cleaning. The apparatuses and methods improve the focusing of sonic waves on workpieces, resulting in improved cleaning of the workpieces.

In one embodiment, a sonic cleaning system is provided. The sonic cleaning system includes a tank configured to contain a liquid that enables propagation of sonic waves and an insert disposed within the tank. The insert includes a first end having a first opening and a second end opposite the first end. The second end has a second opening. The insert is configured to receive a workpiece between the first opening and the second opening. The sonic cleaning system further includes a sonic transducer disposed next to the second opening.

In another embodiment, a method of sonic cleaning a workpiece is provided. The method includes filling a tank with a liquid, wherein the tank includes a sonic transducer and an insert, placing the workpiece in the insert, and activating the sonic transducer.

In yet another embodiment, a sonic cleaning system is provided. The sonic cleaning system includes a tank configured to contain a liquid that enables propagation of sonic waves and an insert disposed within the tank. The insert includes a first end having a first opening and a second end opposite the first end. The second end has a second opening. The insert is configured to receive a workpiece between the first opening and the second opening, and the insert is cylindrical. The sonic cleaning system further includes a sonic transducer located within the cylindrical insert.

It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, and may admit other equally effective embodiments.

Embodiments herein generally relate to a sonic cleaning system and a method of sonic cleaning a workpiece. The sonic cleaning system includes one or more tanks filled with a liquid, wherein high frequency waves (e.g., sound waves) propagate through the liquid. One or more workpieces that are to be cleaned are placed into the liquid. High frequency sound waves are generated, such as by an ultrasonic transducer, and propagate through the liquid to the workpieces. The sound waves cause cavitation proximate the workpieces, which releases particles, such as dirt and grease, from the workpieces. Corners of the tanks may attenuate or disperse the sound waves, which prevents the energy in the sound waves from reaching the workpieces, resulting in inefficient cleaning of the workpieces.

As used herein, the term "about" refers to a +/-<NUM>% variation from the nominal value. It is to be understood that such a variation can be included in any value provided herein.

<FIG> illustrates an isometric view of an sonic cleaning system <NUM>, according to one embodiment. As shown, the sonic cleaning system <NUM> includes one or more tanks <NUM>. The sonic cleaning system <NUM> illustrated in <FIG> includes four tanks <NUM>, which are referred to individually as tanks 104A-104D. Although four tanks 104A-104D are illustrated in <FIG>, the sonic cleaning system <NUM> can include any number of tanks <NUM>. Each of the tanks <NUM> can be at least a portion of an individual sonic cleaning system. The tanks <NUM> can be isolated from one another. Each of the tanks <NUM> can be individually filled with a liquid, such as deionized water, that enables propagation of ultrasonic and/or megasonic sound waves. In some embodiments, the liquid includes one or more solvents, cleaning solutions such as standard clean <NUM> (SC-<NUM>) and/or ammonia hydroxide (NH<NUM>OH) and/or hydrogen peroxide (H<NUM>O<NUM>), selective deposition removal reagents (SDR), surfactants, acids, bases, or any other chemicals useful for removing contaminants and/or particulates from a workpiece. Examples of workpieces are components for wafer fabrication equipment.

The sonic cleaning system <NUM> includes one or more power supplies <NUM>. For example, each of the tanks <NUM> may be associated with one of the power supplies <NUM>. As illustrated in <FIG>, the sonic cleaning system <NUM> includes four power supplies <NUM>, referred to individually as power supplies 106A-106D. Each individual tank 104A-104D can be associated with one of the individual power supplies 106A-106D. Fewer or more power supplies may be used. As described in greater detail below, the power supplies <NUM> can supply radio frequency (RF) power to transducers (not shown in <FIG>) located in the tanks <NUM>.

<FIG> illustrates a top plan view of the tank 104A, according to one embodiment. The tank 104A includes walls <NUM>, such as four walls 208A-208D. The tank <NUM> can be square or rectangular when viewed from the top as illustrated in <FIG>. Square and rectangular tanks are easy to manufacture because flat sheets of material forming the walls 208A-208D can be fastened (e.g., welded) together to form the tank 104A. The walls 208A-208D can include rigid materials, such as stainless steel or other metals. Other materials can be used in the walls 208A-208D. Square and rectangular tanks <NUM> also provide structural integrity and can be easily incorporated into larger structures, such as frames and the like (not shown) that hold and/or support the square and/or rectangular tanks <NUM>. Square and rectangular tanks <NUM> can further include weirs (not shown), such as adjustable weirs, that provide overflow from the tanks <NUM>. The tanks <NUM> can have other shapes including any number of sides, such as three sides, five-sides, and six-sides.

The walls 208A-208D intersect at corners 210A-210D. Other embodiments of the tanks <NUM> can include different shapes having walls (e.g., flat walls) that form corners. For example, the tanks <NUM> include five or six sides wherein at least some of the sides form corners.

A sonic transducer <NUM>, is located within the tank 104A. The sonic transducer <NUM> is configured to emit ultrasonic and/or megasonic waves into the liquid in the tank 104A to facilitate cleaning of a workpiece <NUM>. The sonic transducer <NUM> can include piezoelectric actuators or any other suitable mechanisms that generate vibrations at ultrasonic and/or megasonic frequencies of a specific amplitude. The sonic transducer <NUM> can be a single transducer or can include an array of transducers. The sonic transducer <NUM> is oriented to direct ultrasonic energy to a location where the workpiece <NUM> is positioned. In some embodiments, the sonic transducer <NUM> is configured to direct ultrasonic and/or megasonic waves in a direction normal to an edge of the workpiece <NUM>, or at an angle relative to the normal direction. In some embodiments, the sonic transducer <NUM> is dimensioned to be approximately equal in length to a mean or outer diameter or dimension of the workpiece <NUM>. In other embodiments, the sonic transducer <NUM> has a length greater than the length of the workpiece <NUM>. Power is applied to the transducer by the power supply 106A. For example, RF power is supplied to the ultrasonic transducer by the power supply 106A.

In traditional sonic cleaning systems, ultrasonic and/or megasonic waves generated by the transducer are attenuated by corners of the tank in which the transducer is located. For example, the corners of the tanks disperse or otherwise attenuate the ultrasonic and/or megasonic waves generated by the ultrasonic transducers. In addition, traditional sonic cleaning systems have tanks that are much larger than workpieces located therein. In these tanks, the ultrasonic and/or megasonic waves are dispersed through the large tanks and are not sufficiently focused on the workpieces. Accordingly, the energy generated by the ultrasonic transducers in traditional sonic cleaning systems are not efficiently delivered to the workpiece and sonic cleaning is inefficient.

The sonic cleaning system <NUM> disclosed herein can overcome the deficiencies of conventional sonic cleaning systems by including inserts <NUM> (e.g., cylindrical or otherwise-shaped inserts) in the tanks <NUM>. One or more workpieces (e.g., workpiece <NUM>) are located within the inserts <NUM>. In some embodiments, one or more of the tanks <NUM> include an insert <NUM>, and one or more of the tanks <NUM> do not include an insert. As illustrated in <FIG>, all of the tanks <NUM> include inserts <NUM>, which are referred to individually as inserts 130A-130D. As described in greater detail below, the inserts <NUM> reflect waves emitted by the sonic transducer <NUM>, so the energy generated by the sonic transducer <NUM> remains near the workpiece <NUM>. For example, the waves generated by the sonic transducer <NUM> (<FIG>) are not substantially attenuated by the corners 210A-210D of the tank 104A or dispersed through the whole volume of the tank 104A.

<FIG> illustrates an isometric view of the insert 130A, according to one embodiment. In some embodiments, the insert 130A includes a rigid material, such as a metal. In some embodiments, the insert 130A includes aluminum, titanium, stainless steel, and/or alloy materials, that reflect and/or focus sound waves propagating in a liquid in a tank. The insert 130A can include other materials, such as flexible materials. The materials used in the insert 130A are compatible with liquids in the tank 104A (i.e., the materials of the insert are not substantially corroded or otherwise chemically altered by the liquids). In the embodiment illustrated in <FIG>, the insert 130A is cylindrical. The cylindrical shape focuses and/or reflects the ultrasonic and/or megasonic waves to the workpiece <NUM>. However, other shapes of the insert 130A are contemplated, such as polygonal shaped inserts. In the embodiment illustrated in <FIG>, the insert 130A is in the form of a sleeve that encircles the workpiece <NUM>. However, it is contemplated that the workpiece <NUM> can be placed outside the insert 130A. In some embodiments, the walls of the insert 130A are solid.

As illustrated in <FIG>, the insert 130A includes a first end 332A (e.g., a top end) and an opposite second end 332B (e.g., a bottom end). A wall <NUM> extends between the first end 332A and the second end 332B. The wall <NUM> includes an inner surface 334A and an outer surface 334B. The insert 130A includes a first opening 336A (e.g., a top opening) located proximate the first end 332A and an opposite second opening 336B (e.g., a bottom opening) located proximate the second end 332B. In some embodiments, both the first opening 336A and the second opening 336B are the same size. In some embodiments, a channel <NUM> extends across the insert 130A between the first end 332A and the second end 332B. The insert 130A is round or oval when viewed from the first end 332A, as illustrated in <FIG> and <FIG>. In other embodiments, the insert 130A has other shapes, including octagonal and hexagonal shapes, when viewed from the first end 332A.

<FIG> illustrates a cross-sectioned view of the tank 104A with the insert 130A and the workpiece <NUM>, according to one embodiment. As shown, the tank 104A includes a floor <NUM> that can support the insert 130A and the sonic transducer <NUM>. The tank 104A is at least partially filled with a liquid <NUM>. The liquid <NUM> enables ultrasonic and/or megasonic waves generated by the sonic transducer <NUM> to at least partially propagate throughout the liquid <NUM>. In some embodiments, the liquid <NUM> includes deionized water. In some embodiments, the liquid <NUM> includes one or more solvents, a cleaning solution such as standard clean <NUM> (SC-<NUM>) and/or ammonia hydroxide (NH<NUM>OH) and/or hydrogen peroxide (H<NUM>O<NUM>), selective deposition removal reagent (SDR), surfactants, acids, bases, or any other chemicals useful for removing contaminants and/or particulates from a workpiece. The tank 104A can be filled with other liquids. In some embodiments, the level of the liquid <NUM> is higher than the first end 332A of the insert 130A. In some embodiments, the level of the liquid <NUM> is lower than the first end 332A of the insert 130A, which keeps the waves within the insert 130A and improves cleaning of the workpiece <NUM>. For example, the level of the liquid <NUM> is between about <NUM> and about <NUM> (between about <NUM> in and about <NUM> in) below the first end 332A of the insert 130A. In other embodiments, the level of the liquid <NUM> and the first end 332A are the same height.

As illustrated in <FIG> and <FIG>, the workpiece <NUM> is disposed within the insert 130A so as to be completely submerged and surrounded by the liquid <NUM>. As illustrated in <FIG>, the workpiece <NUM> is suspended within the insert 130A. For example, a cord <NUM> or similar device suspends the workpiece <NUM> within the insert 130A. The cord <NUM> is used in a generic sense and can include any combination of straps, ropes, chains, lines, and other flexible linkages. In some embodiments, the sonic cleaning system <NUM> includes a support <NUM>, such as an overhead beam or similar support, to which the cord <NUM> is attached. The support <NUM> is, for example, a metal bar located at the top of tank 104A above the sonic transducer <NUM> and liquid <NUM>. Accordingly, the support <NUM> and the cord <NUM> are configured to suspend the workpiece within the insert 130A. In other embodiments, other devices are employed to suspend the workpiece <NUM> within the insert 130A. In other embodiments, the workpiece <NUM> is not suspended within the insert 130A.

The workpiece <NUM> can be suspended so as to be located between the first end 332A and the second end 332B of the insert 130A. As such, the workpiece <NUM> is only in direct contact with the liquid <NUM> and the cord <NUM>, and is not directly contacting other components such as the sonic transducer <NUM> or the insert 130A. Traditional sonic cleaning systems include racks or the like that support workpieces. These racks and the like attenuate or absorb energy transferred by the ultrasonic and/or megasonic waves. By suspending the workpiece <NUM> within the insert 130A, more energy transfers near the workpiece <NUM> to clean the workpiece <NUM> than with traditional sonic cleaning systems. For example, more energy in the form of ultrasonic and/or megasonic waves is available to cavitate liquid proximate the workpiece <NUM>.

According to the invention, the sonic transducer <NUM> is located at least partially within the insert 130A. For example, the sonic transducer <NUM> can be located proximate the second opening 336B, at least partially within the second opening 336B, at least partially within the insert 130A, or within the insert 130A. By locating the sonic transducer <NUM> at least partially within the second opening 336B and/or at least partially within the insert 130A, or within the insert 130A, the ultrasonic and/or megasonic waves emitted by the sonic transducer <NUM> propagate within the insert 130A and release energy proximate the workpiece <NUM>. For example, ultrasonic and/or megasonic waves emitted by the sonic transducer <NUM> reflect off the inner surface 334A of the insert 130A toward the workpiece <NUM>. Accordingly, the ultrasonic and/or megasonic waves generated by the sonic transducer <NUM> are not attenuated by the corners 210A-210D of tank 104A. Additionally, the ultrasonic and/or megasonic waves are not dispersed through the volume of the tank 104A located outside the insert 130A.

In some embodiments, transducer supports <NUM> are located between the floor <NUM> of the tank 104A and the sonic transducer <NUM>. The transducer supports <NUM> raise the sonic transducer <NUM> a predetermined distance from the floor <NUM> to form a space between the sonic transducer <NUM> and the floor <NUM>. For example, the transducer supports <NUM> raise the sonic transducer <NUM> so that the sonic transducer <NUM> is at least partially within the insert 130A and/or at least partially within the second opening 336B. The space between the sonic transducer <NUM> and the floor <NUM> can mechanically isolate the sonic transducer <NUM> from the walls 208A-208D and the floor <NUM> of the tank 104A. In some embodiments, the space between the floor <NUM> and the sonic transducer <NUM> is less than about <NUM> (about <NUM> in). Larger or smaller spacings can be used. In some embodiments, a portion of the ultrasonic transducer that emits ultrasonic and/or megasonic waves is higher than the second end 332B of the insert 130A, which maintains the waves within the insert 130A.

In some embodiments, insert supports <NUM> raise the second end 332B of the insert 130A from the floor <NUM>. Raising the second end 332B from the floor <NUM> creates a space <NUM> between the second end 332B and the floor <NUM>. The space <NUM> provides for the flow of the liquid <NUM> between the interior and the exterior of the insert 130A. The space <NUM> also isolates (e.g., mechanically isolate) the insert 130A from the walls 208A-208D and floor <NUM> of the tank 104A. In some embodiments, the space <NUM> is less than about <NUM> (about <NUM> in). In some embodiments, the space <NUM> is less than about <NUM> (about <NUM> in). In some embodiments, the space <NUM> is less than about <NUM> (<NUM> in). In some embodiments, the second end 332B is located proximate and/or in contact with the floor <NUM>.

During use of the sonic cleaning system <NUM>, one or more of the tanks <NUM> is at least partially filled with the liquid <NUM> as described above. Referring to the operation of the tank 104A, the workpiece <NUM> can be suspended by the cord <NUM> or other device within the insert 130A. The sonic transducer <NUM> is activated and emits ultrasonic and/or megasonic waves within the liquid <NUM>. Because the sonic transducer <NUM> is at least partially located within the insert 130A, most of the waves emitted by sonic transducer <NUM> remain within the insert 130A. For example, the waves are not substantially attenuated and/or dispersed by the corners 210A-210D of the tank 104A. In addition, the waves generated by the sonic transducer <NUM> reflect off the curved inner surface 334A of the insert 130A and toward the workpiece <NUM>. Accordingly, more energy is transferred near the workpiece <NUM> than with traditional sonic cleaning systems, resulting in more cavitation than with traditional sonic cleaning systems.

In addition to the foregoing, the workpiece <NUM> can be suspended within the insert 130A, as illustrated in <FIG>. Therefore, racks and other devices that may attenuate and/or disperse waves generated by the sonic transducer <NUM> are not located within the insert 130A. The result is more cavitation near the workpiece <NUM>, and thus improved cleaning of the workpiece.

<FIG> illustrates a flow chart of method <NUM> operations for sonic cleaning of a workpiece, according to one embodiment. The method <NUM> can be stored or accessible to a system controller (not shown) of the sonic cleaning system <NUM> as computer readable media containing instructions, that when executed by a processor of the system controller, cause the sonic cleaning system to perform the method. Any of the individual operations of method <NUM> can be performed in any of the tanks <NUM> of the sonic cleaning system <NUM> described above.

The method <NUM> begins at operation <NUM>, wherein a tank (e.g., the tank 104A) is filled with a liquid (e.g., the liquid <NUM>). The tank includes a sonic transducer (e.g., the sonic transducer <NUM>) and an insert (e.g., the insert 130A).

At operation <NUM>, a workpiece (e.g., the workpiece <NUM>) is placed in the tank. The workpiece can be placed by any conventional method, such as by hand or by a mechanical device configured to place the workpiece.

At operation <NUM>, the sonic transducer is activated to clean the workpiece. The sonic transducer can be de-activated once the cleaning is complete.

As described above, a sonic cleaning system includes one or more tanks filled with a liquid, wherein high frequency waves (e.g., sound waves) propagate through the liquid. One or more workpieces that are to be cleaned are placed into the liquid. A method of sonic cleaning a workpiece includes placing the workpiece in an insert disposed within a tank. High frequency sound waves are generated, such as by an ultrasonic transducer, and propagate through the liquid to the workpieces. The sound waves cause cavitation proximate the workpieces, which releases particles, such as dirt and grease, from the workpieces.

Corners of the tanks may attenuate or disperse the sound waves, which prevents the energy in the sound waves from reaching the workpieces, resulting in inefficient cleaning of the workpieces. However, the sonic cleaning system disclosed herein and reduces energy loss in the tanks by reflecting sound waves toward and/or focusing the sound waves on the workpieces, which improves the cleaning efficiency of the sonic cleaning system.

Claim 1:
A sonic cleaning system (<NUM>), comprising:
a tank (104A) configured to contain a liquid (<NUM>) that enables propagation of sonic waves;
an insert (130A) disposed within the tank (104A), the insert (130A) including a first end (332A) having a first opening (336A) and a second end (332B) opposite the first end (332A), the second end (332B) having a second opening (336B), wherein the insert (130A) is configured to receive a workpiece (<NUM>) between the first opening (336A) and the second opening (336B); and
a sonic transducer (<NUM>) disposed next to the second opening (336B), wherein
the tank (104A) comprises a floor (<NUM>) and wherein the sonic transducer (<NUM>) is located a distance from the floor (<NUM>), and characterised in that
the sonic transducer (<NUM>) is at least partially located within the insert (130A).