Apparatus and method for single-or double-substrate processing

Abstract

In a method for treating semiconductor substrates, one or two substrates are positioned in a substrate process chamber and subjected to wet etching, cleaning, rinsing and/or drying steps. During cleaning or rinsing a band of megasonic energy is created within the process chamber to create an active rinse or cleaning zone, and the substrate(s) are translated through the active zone during a rinsing or cleaning process within the chamber.

1 . A method of individually treating substrates, comprising the steps of: 
 (a) providing a process chamber proportioned to enclose no more than two substrates at a time, and enclosing one or two substrates within the process chamber;    (b) exposing the substrates to a first process fluid within the process chamber; and    (c) after step (b), exposing the substrate to a second process fluid within the process chamber.    
   
   
       2 . The method of  claim 1 , wherein step (b) or (c) includes the step of thinning a boundary layer of fluid at the substrate surface.  
   
   
       3 . The method of  claim 2  wherein the first process fluid is an etching fluid and the second process fluid is a rinse fluid.  
   
   
       4 . The method of  claim 2  wherein the step of thinning a boundary layer by directing megasonic energy into the etching fluid in the chamber.  
   
   
       5 . The method of  claim 2  wherein the step of thinning a boundary layer includes directing etching fluid into the chamber in a direction transverse to the orientation of the substrate.  
   
   
       6 . The method of  claim 3  wherein the etching fluid includes at least one of the group of etching fluids consisting of hydrofluoric acid, ammonium fluoride, and buffered oxide.  
   
   
       7 . The method of  claim 3  further including the step of removing the bulk etching fluid from the chamber.  
   
   
       8 . The method of  claim 7  wherein the chamber includes a container fluidly coupled to the chamber, and wherein the removing step includes suctioning the etching fluid into the container.  
   
   
       9 . The method of  claim 8  wherein prior to the suctioning step the container is sealed and maintained at a negative pressure, and wherein the removing step includes opening a valve between the chamber and the container, causing the etching fluid to be drawn into the container.  
   
   
       10 . The method of  claim 7  wherein the removing step includes cascading rinse water through the chamber to flush out the etching fluid.  
   
   
       11 . The method of  claim 7  including the step of directing megasonic energy into rinse fluid in the chamber during the rinsing step.  
   
   
       12 . The method of  claim 11  wherein the directing step includes forming a band of megasonic energy propagating towards a surface of the substrate, and wherein the method further includes moving the substrate through the band in an edgewise direction to cause substantially the entire surface of the substrate to pass through the band.  
   
   
       13 . The method of  claim 12  wherein the megasonic energy induces thinning of a boundary layer on the portion of the substrate passing through the band.  
   
   
       14 . The method of  claim 12  wherein during step (c) a lower region of the chamber contains rinse fluid and an upper region of the chamber contains gas, wherein the band is adjacent to a gas-liquid interface between the rinse fluid and gas.  
   
   
       15 . The method of  claim 12  wherein the substrate includes a face having a surface area, and wherein approximately 30% or less of the surface area of the face is positioned within the band during the moving step.  
   
   
       16 . The method of  claim 12 , wherein the moving step includes passing the substrate through the band a plurality of times.  
   
   
       17 . The method of  claim 14  wherein the moving step includes passing the substrate through the gas-liquid interface into the upper region of the chamber.  
   
   
       18 . The method of  claim 17 , including passing the substrate through the gas-liquid interface a plurality of times.  
   
   
       19 . The method of  claim 17  further including the step of directing rinse water onto a portion of the substrate within the upper region of the chamber.  
   
   
       20 . The method of  claim 12  wherein the megasonic energy is propagated in a direction normal to the substrate surface.  
   
   
       21 . The method of  claim 12  wherein the megasonic energy is propagated at an angle that is less than normal to the substrate surface.  
   
   
       22 . The method of  claim 1  wherein the first process fluid is a cleaning fluid and the second process fluid is a rinse fluid.  
   
   
       23 . The method of  claim 22 , further including directing megasonic energy into the cleaning fluid, forming a band of megasonic energy propagating towards a surface of the substrate, and wherein the method further includes moving the substrate through the band in an edgewise direction to cause substantially the entire surface of the substrate to pass through the band.  
   
   
       24 . The method of  claim 23 , wherein the moving step includes passing the substrate through the band a plurality of times.  
   
   
       25 . The method of  claim 23  wherein the megasonic energy induces thinning of a boundary layer on the portion of the substrate passing through the band.  
   
   
       26 . The method of  claim 23  wherein during step (c) a lower region of the chamber contains cleaning fluid and an upper region of the chamber contains gas, wherein the band is adjacent to a gas-liquid interface between the cleaning fluid and gas.  
   
   
       27 . The method of  claim 23  wherein the substrate includes a face having a surface area, and wherein approximately 30% or less of the surface area of the face is positioned within the band during the moving step.  
   
   
       28 . The method of  claim 26  wherein the moving step includes passing the substrate through the gas-liquid interface into the upper region of the chamber.  
   
   
       29 . The method of  claim 28 , including passing the substrate through the gas-liquid interface a plurality of times.  
   
   
       30 . The method of  claim 23  wherein the megasonic energy is propagated in a direction normal to the substrate surface.  
   
   
       31 . The method of  claim 23  wherein the megasonic energy is propagated at an angle that is less than normal to the substrate surface.  
   
   
       32 . The method of  claim 23 , further including the step of causing cleaning fluid to flow through the chamber.  
   
   
       33 . The method of  claim 32 , wherein the cleaning fluid flows from a bottom portion of the chamber to an upper portion of the chamber.  
   
   
       34 . The method of  claim 26 , wherein the megasonic energy induces microcavitation in the band, and wherein the method further includes diffusing a gas into the cleaning fluid at the gas-liquid interface to increase the rate of microcavitation in the band.  
   
   
       35 . The method of  claim 23 , further including inducing acoustic streaming within the cleaning fluid by imparting megasonic energy into the cleaning fluid in a region beneath the band.  
   
   
       36 . The method of  claim 22  wherein the method further includes exposing the substrate to an etching fluid in the chamber.  
   
   
       37 . The method of  claim 1  wherein the first process fluid is a rinse fluid and the second process fluid is a drying vapor and wherein step (c) is a drying step.  
   
   
       38 . The method of  claim 1  wherein the first process fluid is a chemical treatment fluid, the second process fluid is a rinse fluid, and wherein the method further includes the step of: 
 (d), after step (c) exposing the substrate to a drying vapor within the process chamber.    
   
   
       39 . The method of  claim 37  or  38  wherein the drying step includes removing bulk fluid from the chamber, and introducing a drying vapor into the chamber.  
   
   
       40 . The method of  claim 37  or  38  wherein, during the drying step a lower region of the chamber contains rinse fluid, and wherein the drying step includes forming an atmosphere of drying vapor in an upper region in the chamber, and withdrawing the substrate from bulk fluid in a lower region of the chamber into the upper region of the chamber.  
   
   
       41 . The method of  claim 40  further including directing megasonic energy into the rinse fluid, forming a band of megasonic energy propagating towards a surface of the substrate, wherein the withdrawing step causes the substrate to pass through the band, and wherein the megasonic energy induces thinning of a boundary layer on the portion of the substrate passing through the band.  
   
   
       42 . The method of  claim 41  wherein the withdrawing step is performed at a rate of approximately 8-30 mm/sec.  
   
   
       43 . The method of  claim 41  wherein the megasonic energy is propagated in a direction normal to the substrate surface.  
   
   
       44 . The method of  claim 41  wherein the megasonic energy is propagated at an angle that is less than normal to the substrate surface.  
   
   
       45 . The method of  claim 40  wherein the withdrawing step is performed slowly, causing removal of fluid from the substrate surface using a surface tension gradient.  
   
   
       46 . The method of  claim 45  wherein the withdrawing step is performed at a rate of approximately 0.25-5 mm/sec.  
   
   
       47 . The method of  claim 37  or  38  wherein the drying step includes the steps of exposing the substrate to a process fluid in the chamber, performing a quick dump to discharge the process fluid from the chamber, leaving residual process fluid on the surface of the substrate, and introducing a drying vapor into the system, the drying vapor condensing on the surface of the substrate and reducing the surface tension of the residual process fluid, causing the residual process fluid to flow off of the surface.  
   
   
       48 . The method of  claim 47  wherein the quick dump discharges the process fluid in less than approximately 5 seconds.  
   
   
       49 . The method of  claim 47  wherein the drying vapor includes isopropyl alcohol vapor.  
   
   
       50 . The method of  claim 47  further including the step of introducing a heated gas into the chamber to volatilize condensed drying vapor from the surface of the substrate.  
   
   
       51 . The method of  claim 1  wherein step (b) includes exposing the substrate to an etching fluid, and wherein the method further includes the step of exposing the substrate to a cleaning fluid.  
   
   
       52 . The method of  claim 50  wherein the step of exposing the substrate to a cleaning fluid is performed after step (c) and before step (d).  
   
   
       53 . The method of  claim 52 , further including the step of rinsing cleaning fluid from the substrate prior to step (d).  
   
   
       54 . The method of  claim 46  wherein the drying vapor is introduced into the system after the process fluid has been discharged from the chamber.  
   
   
       55 . An apparatus for individually treating substrates, comprising: 
 a process chamber proportioned to enclose no more than two substrates at a time;    a source of a first process fluid fluidly coupled to the process chamber; and    a source of a second process fluid fluidly coupled to the process chamber.    
   
   
       56 . The apparatus of  claim 55  further including a source of drying vapor fluidly coupled to the process chamber.  
   
   
       57 . The apparatus of  claim 55 , further including means for thinning a boundary layer of fluid at the substrate surface when the substrate is disposed in a fluid within the chamber.  
   
   
       58 . The apparatus of  claim 57  wherein the means for thinning a boundary layer includes a chamber and an inlet in the chamber for flowing fluid past the wall and the substrate.  
   
   
       59 . The apparatus of  claim 57  wherein the means for thinning a boundary layer includes a megasonic transducer positioned to direct megasonic energy into fluid in the chamber.  
   
   
       60 . The apparatus of  claim 57  wherein the means for thinning a boundary layer includes an inlet in the chamber oriented to direct fluid into the chamber in a direction transverse to the orientation of the substrate.  
   
   
       61 . The apparatus of  claim 55  further including a sealed negative pressure container coupled to the chamber, and a closed valve between the chamber and the container, the valve moveable to an opened position to cause suction of fluid from the chamber into the container.  
   
   
       62 . The apparatus of  claim 61  including a second sealed negative pressure container coupled to the chamber, and a second closed valve between the chamber and the container, the second valve moveable to an opened position to cause suction of fluid from the chamber into the second container.  
   
   
       63 . The apparatus of  claim 55  including at least one megasonic transducer positioned to direct megasonic energy into fluid in the chamber.  
   
   
       64 . The apparatus of  claim 63  wherein the megasonic transducer is oriented to form a band of megasonic energy propagating towards a surface of a substrate in the chamber, and wherein the apparatus further includes an end effector moveable between upper and lower regions of the chamber for moving the substrate through the band in an edgewise direction to cause substantially the entire surface of the substrate to pass through the band.  
   
   
       65 . The apparatus of  claim 64  wherein the megasonic energy induces thinning of a boundary layer on the portion of the substrate passing through the band.  
   
   
       66 . The apparatus of  claim 67  wherein the lower region of the chamber is configured to contain a fluid and the upper region of the chamber is configured to contain gas, and wherein the band is adjacent to a gas-liquid interface between the rinse fluid and gas.  
   
   
       67 . The apparatus of  claim 64  wherein the substrate includes a face having a surface area, and wherein the band is proportioned such that a maximum of approximately 30% or less of the surface area of the face is positioned within the band when the substrate passes through the band.  
   
   
       68 . The apparatus of  claim 64 , wherein the end effector is configured to move the substrate through the band a plurality of times.  
   
   
       69 . The apparatus of  claim 66  wherein the end effector is configured to pass the substrate through the gas-liquid interface into the upper region of the chamber.  
   
   
       70 . The apparatus of  claim 66 , wherein the end effector is configured to pass the substrate through the gas-liquid interface a plurality of times.  
   
   
       71 . The apparatus of  claim 69  wherein the chamber further includes a source of rinse water fluidly coupled to the upper region of the chamber, the source configured to direct rinse water onto a portion of the substrate within the upper region of the chamber.  
   
   
       72 . The apparatus of  claim 64  wherein the megasonic transducer is oriented to propagate energy in a direction normal to the substrate surface.  
   
   
       73 . The apparatus of  claim 64  wherein the megasonic energy is oriented to propagate energy at an angle that is less than normal to the substrate surface.  
   
   
       74 . The apparatus of  claim 55  wherein the first process fluid is a cleaning solution and the second process fluid is a rinse fluid.  
   
   
       75 . The apparatus of  claim 55  wherein the first process fluid is an etch solution and the second process fluid is a rinse fluid.  
   
   
       76 . The apparatus of  claim 75  wherein the etch solution includes at least one etching fluid from the group consisting of hydrofluoric acid, ammonium fluoride, and buffered oxide.  
   
   
       77 . The apparatus of  claim 66 , wherein the megasonic transducer is further configured to induce microcavitation in the band, and wherein the apparatus further includes a source of gas fluidly coupled to the chamber and a gas outlet in the chamber, the gas outlet positioned to diffuse gas into the cleaning fluid at the gas-liquid interface to increase the rate of microcavitation in the band.  
   
   
       78 . The apparatus of  claim 64 , further including a second megasonic transducer positioned to direct megasonic energy into fluid in the chamber in a region beneath the band.  
   
   
       79 . The apparatus of  claim 78  wherein the second megasonic transducer is configured to induce acoustic streaming in the fluid.  
   
   
       80 . The apparatus of  claim 56  wherein the source of drying vapor directs drying vapor into an upper region of the chamber, and wherein the end effector is configured to withdraw the substrate from fluid in a lower region of the chamber into drying vapor in the upper region of the chamber.  
   
   
       81 . The apparatus of  claim 80  wherein the end effector is configured to withdraw the substrate at a rate of approximately 8-30 mm/sec.  
   
   
       82 . The apparatus of  claim 80  wherein the end effector is configured to withdraw the substrate at a rate of approximately 0.25-5 mm/sec.  
   
   
       83 . The apparatus of  claim 56  wherein the first or second process fluid is rinse fluid, and wherein the apparatus further includes a drain configured to perform a quick dump to discharge rinse fluid from the chamber, leaving residual process fluid on the surface of the substrate, wherein the source of drying vapor is for introducing a drying vapor into the chamber after a quick dump has been performed, such that the drying vapor condenses on the surface of the substrate and reduces the surface tension of the residual process fluid, causing the residual process fluid to flow off of the surface.  
   
   
       84 . The apparatus of  claim 83  wherein the quick dump discharges the process fluid in less than approximately 5 seconds.  
   
   
       85 . The apparatus of  claim 56  wherein the drying vapor includes isopropyl alcohol vapor.  
   
   
       86 . The apparatus of  claim 56  further including a source of a heated gas fluidly coupled to the chamber to evaporate condensed drying vapor from the surface of the substrate.  
   
   
       87 . The apparatus of  claim 86 , further including an outlet in the chamber for directing the heated gas in the chamber, and an end effector moveable to translate the substrate past the outlet to accelerate evaporation.  
   
   
       88 . The apparatus of  claim 56  wherein the first process fluid is an etch fluid, and the second process fluid is a rinse fluid and wherein the apparatus further includes a source of cleaning fluid fluidly coupled to the chamber.  
   
   
       89 . The apparatus of  claim 55  wherein the chamber includes a substrate-receiving member having a notch proportioned to receive a lower edge of a substrate, and wherein the apparatus further includes: 
 an end effector including a pair of substrate-receiving members, each substrate-receiving member having at least one stabilizing element and at least one engaging element, the end effector being moveable between 
 a first position within the process chamber wherein a lower edge of a substrate is in contact with the notch and wherein each stabilizing element is positioned at a lateral edge of the substrate to restrict movement of the substrate; and  
 a second position wherein the lower edge of the substrate is withdrawn from contact with the notch and wherein each engaging element supports a lateral edge of the substrate.  
   
   
   
       90 . The apparatus of  claim 89  wherein the at least one stabilizing element includes a slot oriented to receive a substrate edge within the slot to restrict movement of the substrate in a direction transverse to a plane containing the substrate, and a stabilizing member extending towards a substrate edge to restrict movement of the substrate in a lateral direction.