Method and apparatus to process substrates with megasonic energy

Abstract

A variety of techniques may be employed, alone or in combination, to enhance contact between a processed substrate and applied megasonic energy. In accordance with one embodiment of the new invention, the vibration plate is brought into intimate contact with one surface of the substrate, while cleaning or processing fluid contacts the other. In accordance with an alternative embodiment of the present invention, a reflecting surface may be provided to cause emanated energy to be reflected back into the near field and make it more uniform. In accordance with another alternative embodiment of the present invention, energy may be transferred across a substrate bounded on both sides by liquid with incidence of megasonic energy that is either normal to the substrate surface or within a critical range of incident angles. In yet another embodiment, generated dilatational waves may be converted to surface waves prior to contacting the substrate.

1 . An apparatus configured to process a substrate with megasonic energy, the apparatus comprising: 
 a processing region configured to receive a processing fluid;    a megasonic energy source; and    a vibration member in physical contact with the megasonic energy source and with at least a portion of a substrate to be processed in the processing region, a combined thickness of the substrate and the vibration member being about ±30% of an odd one-quarter wavelength of a megasonic energy applied by the source in order to transfer the megasonic energy across the substrate.    
     
     
         2 . The apparatus of  claim 1  wherein the element comprises one of a substrate to be processed, a substrate support, an electrode, a chemical mechanical polishing pad, a brush, a wall defining the processing region, and a substrate cassette member.  
     
     
         3 . The apparatus of  claim 1  wherein the megasonic energy source comprises one of a piezoelectric crystal, a mechanical transducer, and a megasonic nozzle.  
     
     
         4 . The apparatus of  claim 1  wherein: 
 the element comprises a substrate to be processed having at least a part of a first side in physical contact with the vibration member; and    the apparatus further comprises a processing member proximate to a second side of the substrate opposite to the first side, the processing member selected from the group consisting of an electrode, a chemical mechanical polishing pad, a diffraction grating, spray nozzle, megasonic nozzle jet, and a scrubbing brush.    
     
     
         5 . The apparatus of  claim 1  wherein: 
 the apparatus further comprises a mechanism configured to impart motion to the substrate relative to at least one of a substrate support and the processing fluid.    
     
     
         6 . The apparatus of  claim 1  further comprising at least one of a reflecting surface and a gas/liquid interface configured to reflect the megasonic energy toward the substrate.  
     
     
         7 . The apparatus of  claim 1  wherein the processing region is enclosed within a plurality of walls.  
     
     
         8 . The apparatus of  claim 7  wherein the plurality of walls allow processing at other than atmospheric pressure within the processing region.  
     
     
         9 . The apparatus of  claim 1  wherein the processing fluid comprises at least one of a gas, a liquid, a vapor, a solid, and combinations thereof.  
     
     
         10 . A method of processing a substrate, said method comprising the steps of: 
 placing at least one substrate into a process vessel;    making contact between at least a part of the substrate and at least a part of a vibration member;    introducing at least one processing fluid into the processing vessel;    contacting at least a part of the substrate with at least one of the processing fluids; and    applying megasonic energy, wherein the applying megasonic energy step occurs at least one of before, during and after the introducing processing fluid step.    
     
     
         11 . The method of  claim 10  wherein the sum of the thickness of the substrate and the thickness of the vibration member equals within ±30% of an odd multiple one-quarter wavelength (nλ/4, n=1,3,5 . . . ) of the applied megasonic energy.  
     
     
         12 . The method of  claim 10  wherein at least one of a reflecting member, a vessel surface, a second megasonic energy source, and a gas-liquid interface reflects megasonic energy back onto the substrate.  
     
     
         13 . The method of  claim 12  wherein the reflecting member is comprised of a material of thickness equal to within ±30% of an odd multiple one-quarter wavelength of the applied megasonic energy.  
     
     
         14 . The method of  claim 12  wherein there is relative motion between the reflecting member and at least one of the substrate, the processing fluid, and the vessel.  
     
     
         15 . The method of  claim 12  wherein at least one processing fluid is at least one of introduced and removed through at least one of holes, slots, cavities and tubes in at least one of the reflecting member and the vibration member.  
     
     
         16 . The method of  claim 10  wherein one of a chemical mechanical polishing step and a brush cleaning step operate at least one of prior to, during, and after the application of megasonic energy.  
     
     
         17 . The method of  claim 10  wherein the introduction of processing fluid causes at least a part of the substrate to be wetted by at least one of submerging, spraying, and condensing of a vapor.  
     
     
         18 . The method of  claim 10  wherein the process vessel is pressurized at least one of prior to, during, and after the application of megasonic energy.  
     
     
         19 . The method of  claim 18  wherein a maximum pressure is in the range of 1 to 500 atmospheres.  
     
     
         20 . The method of  claim 10  wherein an electrochemical process is conducted at least one of prior to, during and after the application of megasonic energy.  
     
     
         21 . (canceled)  
     
     
         22 . The method of  claim 10  wherein radiation is applied at least one of prior to, during and after the application of megasonic energy.  
     
     
         23 . The method of  claim 22  wherein application of the radiation serves to remove at least one of contaminant particles and processing fluid from the substrate, or serves to modify a portion of the substrate surface.  
     
     
         24 . (canceled)  
     
     
         25 . The apparatus of  claim 24  wherein the element comprises one of a substrate to be processed, a substrate holder, an electrode, a chemical mechanical polishing pad, a wall defining the processing region, and a substrate cassette member.  
     
     
         26 . (canceled)  
     
     
         27 . The apparatus of  claim 24  wherein: 
 the element comprises a substrate to be processed having a first side proximate to the vibration member; and    the apparatus further comprises a processing member proximate to a second side of the substrate opposite to the first side, the processing member selected from the group consisting of an electrode, a chemical mechanical polishing pad, a diffraction grating, a spray nozzle, and a scrubbing brush.    
     
     
         28 - 51 . (canceled)  
     
     
         52 . An apparatus configured to process a substrate with megasonic energy, the apparatus comprising: 
 a processing region configured to receive a processing fluid;    a flow member configured to control a path of the processing fluid within a tank; and    a megasonic energy source configured to apply megasonic energy to the tank, such that a direction of the megasonic energy conforms to the path.    
     
     
         53 . The apparatus of  claim 52  wherein the flow member exhibits a streamlined cross-sectional profile configured to allow the passage of fluid past the member to the substrate.  
     
     
         54 . The apparatus of  claim 53  wherein the flow member comprises at least one of a substrate support, a cassette portion, an electrode, a vibration member, a polishing pad, and a scrubbing brush.  
     
     
         55 . The apparatus of  claim 52  wherein the flow member comprises one of an angled surface and a curved surface configured to reflect the fluid against the substrate.  
     
     
         56 . A method of processing a substrate with megasonic energy, the method comprising: 
 flowing a processing fluid within a tank containing a substrate; and    applying megasonic energy to the tank such that a direction of the megasonic energy conforms to a path of the processing fluid.    
     
     
         57 . The method of  claim 56  wherein the megasonic energy conforms to a flow of processing fluid to the substrate around a member having a streamlined cross-sectional profile.  
     
     
         58 . The method of  claim 56  wherein the megasonic energy conforms to a flow of processing fluid to the substrate reflected from one of an angled surface and a curved surface.  
     
     
         59 - 77 . (canceled)  
     
     
         78 . A method of claim  66  wherein radiation is applied at least one of prior to, during and after the applying megasonic energy.  
     
     
         79 . The method of  claim 78  wherein the radiation is comprised of at least one of microwave, ultraviolet, infrared and electromagnetic induction.  
     
     
         80 . The method of claim  66  wherein electrochemical processing occurs at least one of prior to, during and after the applying megasonic energy.  
     
     
         81 . The method of claim  66  wherein at least one of chemical mechanical polishing processing, brush scrubbing, aerosol jet cleaning, and laser shock processing occur at least one of prior to, during and after the applying megasonic energy.  
     
     
         82 . An apparatus configured to process a substrate with megasonic energy, comprising: 
 a processing region configured to receive a processing fluid;    a vibration member in physical contact with a megasonic energy source and configured to support a substrate in the processing region within a near field of megasonic energy incident in a first direction from the vibration member; and    an element configured to direct megasonic energy to the near field from a second direction different from the first direction.    
     
     
         83 . The apparatus of  claim 82  wherein the element comprises a surface configured to reflect megasonic energy back to the near field.  
     
     
         84 . The apparatus of  claim 83  wherein the surface comprises at least one of a machined, a contoured, and a roughened surface.  
     
     
         85 . The apparatus of  claim 83  wherein the surface comprises a curved plate.  
     
     
         86 . The apparatus of  claim 83  wherein the surface comprises a gas/liquid interface.  
     
     
         87 . The apparatus of  claim 83  wherein the surface is configured to be moved relative to the substrate.  
     
     
         88 . The apparatus of  claim 82  wherein the element comprises a second megasonic energy source oriented in the second direction.  
     
     
         89 . An apparatus configured to process a substrate with megasonic energy, comprising: 
 a processing region configured to receive a processing fluid; and    a megasonic energy source configured to output megasonic energy having at least one of a user-controlled and variable frequency, power, and pulse width, to a substrate present within the processing region.    
     
     
         90 . The apparatus of  claim 82  further comprising a second megasonic energy source in sonic communication with the substrate, such that a far field of megasonic energy impinging the substrate from the second source overlaps a near field of megasonic energy impinging from the substrate from the first source.  
     
     
         91 . The apparatus of  claim 89  wherein the megasonic energy source is configured such that at least one of a magnitude, a frequency, and a pulse width of a driving voltage is varied about a set point according to at least one of a sinusoidal signal, a randomly fluctuating signal, and a stepwise sequence.  
     
     
         92 - 208 . (canceled)  
     
     
         209 . The apparatus of  claim 1  wherein the megasonic energy source is configured to vary a parameter of applied megasonic sonic energy selected from a phase, a frequency, a power, and a pulse width.  
     
     
         210 . The method of  claim 10  further comprising varying a parameter of the applied megasonic energy selected from a phase, a frequency, a power, and a pulse width.  
     
     
         211 . The apparatus of  claim 52  wherein the megasonic energy source is configured to vary a parameter of applied megasonic sonic energy selected from a phase, a frequency, a power, and a pulse width.  
     
     
         212 . The method of  claim 56  further comprising varying a parameter of the applied megasonic energy selected from a phase, a frequency, a power, and a pulse width.  
     
     
         213 . The apparatus of  claim 82  wherein the megasonic energy source is configured to vary a parameter of applied megasonic sonic energy selected from a phase, a frequency, a power, and a pulse width.