Method of manufacturing fluid pump

Information

  • Patent Grant
  • 6533951
  • Patent Number
    6,533,951
  • Date Filed
    Thursday, July 27, 2000
    24 years ago
  • Date Issued
    Tuesday, March 18, 2003
    21 years ago
Abstract
A method of manufacturing a pump [10] for pumping various primary fluids. A body is formed from silicon dies [102,104]. A primary fluid channel [110] is formed in the body and a primary fluid supply [122] is coupled to the primary fluid channel [110] to supply a primary fluid to the primary fluid channel [110]. A mechanism for introducing a secondary fluid to an interface region of the primary fluid channel [110] is formed in the body. An energy delivery device is formed in the body to deliver energy to an interface between region between the primary fluid and the secondary fluid to create a thermal gradient along the fluid interface. The thermal gradient results in a surface tension gradient along the interface. The primary fluid will move to compensate for the surface tension gradient. Various semiconductor fabrication processes can be used to form the elements on the body.
Description




FIELD OF THE INVENTION




The present invention relates generally to pumping devices, and more particularly to a method of manufacturing a fluid pump, such as a microscale fluid pump, using semiconductor fabrication techniques




BACKGROUND OF THE INVENTION




It is well known to utilize microscale fluid pumps to pump various fluids. The term “microscale,” as used herein, refers to an apparatus or method using a minimum amount of fluid to effectively perform a function. Many microscale pumps incorporate thermal technology, whereby heat is used to move the fluid. For example, in a bubble jet printer ink in a channel is heated to a boil to create a bubble until the pressure ejects a droplet of the ink out of a nozzle. The bubble then collapses as the heating element cools, and the resulting vacuum draws fluid from a reservoir to replace the fluid that was ejected from the channel. Thermal technology requires that the fluid to be pumped be resistant to heat, i.e. capable of being boiled without significant breakdown. Also, the need for a cooling period between ejecting successive droplets from a nozzle places speed limitations on thermal microscale pumps.




Piezoelectric microscale pumps, such as that disclosed in U.S. Pat. No. 5,224,843, have a piezoelectric crystal in the fluid channel that flexes when an electric current flows through it to force a drop of fluid out of a nozzle. Piezoelectric technology is faster and provides more control over the fluid movement as compared to thermal technology. Also, because the fluid to be pumped is not heated significantly, the fluid can be selected based on its relevant properties rather than its ability to withstand high temperatures. However, piezoelectric microscale pumps are complex and thus expensive to manufacture. U.S. Pat. Nos. 5,362,213 and 5,499,409 disclose microscale pumps having movable parts. Such pumps are relatively complex and required high maintenance.




Further, microscale fluid pumps find use in various other applications in which a high degree of control is required and high temperatures are to be avoided. For example, microscale fluid pumps can be used in biological heat-pipe type devices, devices which administer small doses of fluid into a larger stream of fluid, devices which pump various solutions that are unstable when boiled, devices which pump biological materials and other materials that must be maintained at a constant temperature, and other generic pumping applications. Accordingly, there is a need for a microscale fluid pump that is simple in construction and capable of pumping fluid quickly and accurately without boiling the fluid. Further, there is a need for a microscale fluid pump design and manufacturing method that easily can be manufactured using semiconductor fabrication techniques.




It is known to utilize semiconductor manufacturing technology to form devices having fluid channels, For example, U.S. Pat. No. 5,890,745 discloses a fluid coupler that includes a fluid channel formed by etching a semiconductor wafer. However, the fluid coupler disclosed in this patent has no mechanism for moving fluid and merely serves as a conduit between fluid systems.




SUMMARY OF THE INVENTION




An object of the invention is to increase the control accuracy of microscale fluid pumps by employing precision semiconductor manufacturing techniques.




Another object of the invention is to simplify the construction of microscale fluid pumps.




Another object of the invention is to utilize semiconductor fabrication techniques to manufacture a fluid pump.




Another object of the invention is to utilize standard CMOS processes to manufacture a microscale fluid pump.




Another object of the invention is to impart motion to fluid without the need for moving parts or boiling of the fluid.




Another object of the invention is to reduce the power required by microscale fluid pumps.




The invention achieves these and other objects through a first aspect of the invention which is a method for manufacturing a fluid pump comprising the steps of defining a primary fluid channel in a body, forming a primary fluid aperture in communication with the primary fluid channel, forming a mechanism on the body for introducing a secondary fluid to an interface region of the primary fluid channel, and forming an energy delivery device proximate the interface region.











BRIEF DESCRIPTION OF THE DRAWINGS




Other features and advantages of the present invention will become apparent from the following description of the preferred embodiments of the invention, and the accompanying drawings, wherein:





FIG. 1

is a top view of a pump in accordance with a first preferred embodiment of the invention with portions rendered transparent;





FIG. 2

is a perspective view of the pump of

FIG. 1

;





FIG. 3

is a sectional view taken along line


3





3


of

FIG. 1

;





FIG. 4

is an enlarged view of portions of

FIG. 3

;





FIGS. 5-13

illustrate the steps of manufacturing a first die of the first preferred embodiment;





FIGS. 14-19

illustrate the steps of manufacturing a second die of the first preferred embodiment;





FIGS. 20 and 21

illustrate a first preferred procedure of bonding the first and second dies of the first preferred embodiment;





FIG. 22

illustrates a second preferred procedure of bonding the first and second dies of the first preferred embodiment;





FIG. 23

illustrates a third preferred procedure of bonding the first and second dies of the tint preferred embodiment.





FIG. 24

is a top view of a pump in accordance with a second preferred embodiment of the invention with portions rendered transparent;





FIG. 25

is a perspective view of the pump of

FIG. 24

;





FIG. 26

is an enlarged sectional view taken along line


26





26


of

FIG. 25

;





FIG. 27

is a perspective view of a pump in accordance with a third preferred embodiment of the invention;





FIG. 28

is a perspective view of a pump in accordance with a fourth preferred embodiment of the invention; and





FIGS. 29-33

illustrate the steps of manufacturing a first die of the second preferred embodiment.











DETAILED DESCRIPTION OF THE INVENTION





FIGS. 1-4

illustrate a first preferred embodiment of the invention. The preferred embodiment is formed from a silicon substrate using known semiconductor fabrication techniques as described in detail below. However, the invention can be formed of various materials using various fabrication techniques. Microscale pump


10


includes silicon substrate


100


(serving as a pump body) having primary fluid channel


110


formed therein, through an etching process or the like. Primary fluid ports


120


communicate with primary fluid channel


110


. One of primary fluid ports


120


can be coupled to supply


122


of primary fluid to be pumped (as illustrated schematically by the dotted line in

FIG. 3

) and the other of primary fluid ports


120


can be coupled to a nozzle or any other orifice, channel, or the like through which fluid is to be ejected or otherwise transported. As will become apparent below, microscale pump


10


can be operated in either a forward or reverse direction and thus primary fluid ports


120


are interchangeable with one another.




As best illustrated in

FIGS. 3 and 4

, secondary fluid channel


130


is formed in substrate


100


in communication with an interface region of primary fluid channel


110


. Secondary fluid channel


130


is coupled to external supply


132


of a secondary fluid, such as a pressurized supply of nitrogen, hydrogen, air or oxygen. Secondary fluid channel


130


and external supply


132


are operative to introduce the secondary fluid to the interface region of primary fluid channel


110


. The secondary fluid is used to create a fluid interface with the primary fluid, as described in detail below, and preferably is not pumped by microscale pump


10


.




As illustrated in

FIG. 4

a first insulating layer, such as a thermal oxide layer


140


, is grown on a surface of substrate


100


using techniques described below. Heating elements


150


and


160


are formed on insulating layer


140


respectively at opposing sides of the interface region of primary fluid channel


110


. Heating elements


150


and


160


can include resistive elements and can each comprise doped polysilicon layer


152


/


162


deposited on thermal oxide layer


140


and aluminum layers


154


/


164


formed thereon to serve as an electrical conductor. As illustrated in

FIG. 1

, aluminum layer


154


defines contact pads


158


and conductor


159


and aluminum layer


164


defines contact pads


168


and conductor


169


. Accordingly, electric power can be supplied to the resistive elements of heating elements


150


and


160


to generate heat at the interface region. Silicon dioxide layer


156


/


166


can be formed as a second insulating layer to insulate the other components the manufacturing method of the first preferred embodiment is discussed in detail below.




During operation of microscale pump


10


, a primary fluid to be pumped is supplied to primary fluid channel


110


through one of primary fluid ports


120


. Further, a relatively small metered amount of a secondary fluid, such as a gas, is introduced into the interface region of primary fluid channel


110


through secondary fluid channel


130


to form bubble


170


of the secondary fluid as illustrated in

FIGS. 3 and 4

. A fluid interface is thus defined between the primary fluid and the secondary fluid in the interface region of primary fluid channel


110


. In this state, contact pads


158


and


168


can be coupled to a source of electric power that is controlled in a desired manner to selectively supply current to one of heating elements


150


or


160


. For example, when electric current is supplied to heating element


150


, through contact pads


158


and conductor


159


, heating element


150


generates heat at one side of the interface region. Accordingly, a temperature gradient is defined in the interface region along the interface between the primary fluid and the secondary fluid. Since the surface tension between two dissimilar fluids is dependent on the temperature at the interface of the fluids, a surface tension gradient is formed along the fluid interface. The primary fluid will naturally move in the direction of decreasing temperature, i.e. the direction indicated by arrow x in

FIGS. 1 and 2

, to compensate for the surface tension gradient. Accordingly, motion is imparted to the primary fluid in response to activation of heating element


150


. Heating element


160


can be activated in a similar manner to move the primary fluid in the direction of arrow y. Further, heating elements


150


and


160


can be activated together or separately to varying degrees to precisely control the temperature gradient along the fluid interface and thus precisely control movement of the primary fluid.




The method of manufacturing the first preferred embodiment will be described in detail below with respect to

FIGS. 5-21

. The preferred embodiment is comprised of two dies and each die is processed simultaneously with other dies as part of a respective wafer which is subsequently cut into plural dies, as is well known. However, for the sake of clarity, only one die of the wafer is illustrated and discussed. Accordingly, the various layers and films are not illustrated on the sides of each die because the die is processed as part of a larger wafer. Also, the term “die, as used herein, refers to any body place, such as a wafer, portion of a wafer, or the like. Specifically substrate


100


can be comprised of first die


102


and second die


104


(see FIG.


3


), made of silicon for example. Dies


102


and


104


can be processed separately and subsequently joined together through a bonding process or the like. Beginning with die


102


as bare silicon illustrated in

FIG. 5

, thermal oxide layer


140


is grown thereon, as illustrated in

FIG. 6

for the purpose of insulating the electronics from the silicon beneath. For example a steam oxidation process can be performed at 1100° C., for 240 minutes. This process will yield about 1.3 microns of oxide, i.e. thermal oxide layer


140


will be about 1.3 microns thick. However, 2000-3000 angstroms of oxide is adequate to insulate the silicon from the electronics. The additional thickness of thermal oxide layer


140


allows for possible degradation or damage during later processes.




Next, as illustrated in

FIG. 7

, doped polysilicon layer


152


/


162


of polysilicon is deposited on thermal oxide layer


140


using a low pressure chemical vapor deposition (LPCVD) process. Polysilicon layer


152


/


162


can be n-doped or p-doped. For example the LPCVD process can be conducted for 120 minutes at 610° C. This recipe will yield polysilicon layer


152


/


162


of about 3000 angstroms in thickness on both faces of die


102


. The next step is to anneal polysilicon layer


152


/


162


to reduce the resistively thereof to about 25 ohms/mm


2


(about a factor of ten difference with respect to the polysilicon layer


152


/


162


prior to annealment). The annealment step can be accomplished by heating die


102


in a nitrogen environment at 1 atmosphere and 900° C. for about one to two hours.




Next, as illustrated in

FIG. 8

, pads


158


/


168


and conductors


159


/


169


can be formed by sputtering aluminum layer


154


/


164


on polysilicon layer


152


/


162


, on the top face of die


102


. A photoresist lithography process can be used to etch the pattern of pads


158


/


168


and conductors


159


/


169


. For example, wafer


102


can be dehydrated and coated with HMDS (Hexamethyldisilazane) to facilitate adhesion between aluminum layer


154


/


164


and the subsequent photoresist layer. A photoresist layer can then be coated on aluminum layer


154


/


164


and spun to about 1.2 microns in thickness. The layer can be soft baked for about 60 seconds at 90° C., exposed, developed, and hard bake for about 45 minutes at 120° C. A wet etch process can be used until portions of aluminum layer


154


/


164


beneath the exposed areas are removed to form the desired patterns in aluminum layer


154


/


164


. Subsequently, the photoresist layer can be stripped and die


102


can be cleaned in de-ionized water to yield the pattern illustrated in FIG.


9


. Of course since

FIG. 9

is in cross section, the entire pattern is not visible. However,

FIGS. 1 and 2

above illustrate the pattern more clearly. Note that, polysilicon layer


152


/


162


on the front and back of die


102


will be exposed to the aluminum etchant but will not be removed or otherwise affected thereby.




Next, polysilicon layer


152


/


162


is patterned into resistive elements (leaving conductors


159


/


169


and pads


158


and


168


) using a similar photolithography process as that described above. In particular, a zig-zag or other pattern can be formed of polysilicon layer


152


/


162


to form resistive heating elements. The etching process will stop at thermal oxide layer


140


but polysilicon layer


152


/


162


on the back face will be removed in the wet etch bath as illustrated in FIG.


10


. The photoresist can then be stripped and die


102


can be cleaned.




Next, the electrical components are insulated with silicon dioxide layer


156


/


166


deposited with an LPCVD process to a thickness of about 3000 angstroms, as illustrated in FIG.


11


. Both faces of die


102


are subject to the LPCVD process to form a conformal layer that will follow the existing contours formed by the etching steps discussed above, as illustrated in FIG.


11


. Holes are then formed in silicon dioxide layer


156


/


166


to remove the insulation from contact pads


158


/


168


and from the surface where the bulk silicon must be etched to form secondary fluid channel


130


as illustrated in

FIG. 12. A

plasma etching process can be accomplished in a reactive ion etcher (RIE) so only the top side is etched to form secondary fluid channel


130


, as illustrated in FIG.


13


. In particular, a thick lithography process can be used to pattern the hole and thermal oxide layer


140


can be etched using the RIE process. The same photoresist layer can be used in an inductively coupled plasma (ICP) etching process to get an anisotropic etch all the way through die


102


(this typically requires the attachment of a wafer to the back side of the device wafer to prevent damage to the etcher when the hole though die


102


is completed). The thin membrane of thermal oxide on the back side can be etched, but will be broken by the pressure from the external supply


132


if it is not ruptured during etching.




Second die


104


of the preferred embodiment is formed in the following manner with reference to

FIGS. 14-19

. Thermal oxide layer


142


is grown on silicon die


104


(see

FIG. 14

) as a masking layer as illustrated in FIG.


15


. For example a steam oxidation process at 1100° C. for 240 minutes will yield thermal oxide layer


142


of about 1.3 microns in thickness. Primary fluid channel


110


is then patterned in oxide layer


142


, as illustrated in

FIG. 16

, using the standard lithography process disclosed above. The photoresist is then stripped and wafer


104


is cleaned.




As illustrated in

FIG. 17

, fluid ports


120


are patterned in the silicon after oxide has been selectively removed from these portions of die


104


using the photo resist step disclosed above. The photoresist is then stripped and die


104


is cleaned again. An RIE process can be used to etch primary fluid channel


110


to a specified depth, e.g. 100 micrometers, using oxide layer


142


as a mask, as illustrated in FIG.


28


. Subsequently, oxide layer


142


can be stripped by submersing die


104


in hydrofluoric acid until hydrophobic, as illustrated in

FIG. 19

(this step can be omitted if the oxide layer is desirable in the bonding process as discussed below).




Dies


102


and


104


are bonded to form substrate


100


in the following manner. First, epoxy layer


200


is spread onto one of dies


102


and


104


, as illustrated in FIG.


20


. Dies


102


and


104


are then aligned and held under pressure to form a bond as epoxy layer


190


cures, as illustrated in FIG.


21


. Alternatively, dies


102


and


104


can be aligned and placed under pressure while being heated to a moderate temperature (preferably below 500° C. to avoid melting the aluminum) to form a fusion bond as illustrated in FIG.


22


. Further, as illustrated in

FIG. 23

, oxide layer


142


can be left on the lower surface of die


104


and fusion can be accomplished between oxide layer


142


and silicon dioxide layer


156


/


166


.





FIGS. 24-26

illustrate a second preferred embodiment of the invention. Microscale pump


200


is similar to microscale pump


10


of the first preferred embodiment. However, microscale pump


200


does not have a secondary fluid channel for introducing a secondary fluid. In microscale pump


200


, bubble


220


is formed, i.e. the secondary fluid is introduced, in-situ. In particular, a pair of electrodes


210


are provided proximate an interface region of primary fluid channel


110


. Electrodes


210


are coupled to an external source of electric power. After an aqueous fluid is introduced into primary fluid channel


110


as the primary fluid, electrodes


210


can be energized, i.e. an electric potential can be placed across electrodes


210


, to thereby dissociate the primary fluid into components of hydrogen and oxygen to form bubble


220


of hydrogen and oxygen in the interface region. Other than the in situ formation of bubble


220


, the structure and operation of microscale pump


200


is similar to that of microscale pump


10


and like reference numerals are used to label similar parts in

FIGS. 5-7

. Any primary fluid can be dissociated or otherwise transformed to form the secondary fluid.





FIGS. 29-33

illustrate the method of manufacturing the second preferred embodiment. First, the steps illustrated in

FIGS. 5-11

disclosed above are accomplished in a manner similar to the manufacturing process of the first preferred embodiment. Then, as illustrated in

FIG. 29

, a photolithography process is used to make a negative of the pattern for electrodes


210


(see

FIG. 24

) in photoresist layer


171


. As illustrated in

FIG. 30

platinum layer


172


(or any other appropriate material) can be deposited, through an evaporation process, to about 3000 angstroms thick over photoresist layer


171


. Die


102


can then be dipped in acetone for approximately 1 hour to dissolve photoresist layer


171


using a “liftoff process”. In such a process, photoresist layer


171


is dissolved away and platinum layer


172


lifts off, except for locations where photoresist layer


171


was not present. This leaves platinum layer


172


only at portions corresponding to electrodes


210


as illustrated in FIG.


31


. Subsequently, electrodes


210


can be insulated with oxide layer


174


, in a manner similar to the process discussed above, as illustrated in FIG.


32


. Oxide layer


174


can then be etched away over contacts and a tip of electrode


210


, in a process similar to that described above, as illustrated in FIG.


33


. Die


104


of the second preferred embodiment can be manufactured similar to die


104


of the first preferred embodiment and the dies can be bonded in any one of the processes described above with respect to the first preferred embodiment.





FIG. 27

illustrates a third preferred embodiment of the invention. Microscale pump


300


is similar to microscale pump


10


of the first preferred embodiment and microscale pump


200


of the second preferred embodiment. However, microscale pump


300


includes plural interface regions each having a mechanism for introducing a secondary fluid, i.e. producing bubble


320


. The mechanism for introducing each bubble


320


of secondary fluid can be similar to that of the first preferred embodiment, i.e. external, or the second preferred embodiment, i.e. in-situ. Microscale pump


300


can create a temperature gradient along one or more fluid interfaces and thus a surface tension gradient along one or more interfaces between the primary fluid and the secondary fluid. Each fluid interface can be used to impart motion to the primary fluid in the manner described above. Because the fluid interfaces are in serial relationship with each other along the flow direction, the pressure or flow volume can be increased as compared to a pump having only one interface region.





FIG. 28

illustrates a fourth preferred embodiment of the invention. Microscale pump


400


is similar to microscale pump


10


of first preferred embodiment and microscale pump


200


of second preferred embodiment. However, microscale pump


400


has a slot opening that supports a long secondary fluid interface oriented appropriately to induce flow when heaters or electrodes


150


and


160


are energized. The high aspect ratio secondary fluid interface provides a large surface area that increase the capacity of the pump. The mechanism for introducing a bubble secondary fluid can be similar to that of first preferred embodiment, i.e. external, or the second preferred embodiment, i.e. in-situ. In addition, a plurality of long bubbles may be utilized to create a multiple fluid interface pump described in the third preferred embodiment.




The secondary fluid can be introduced in any manner. As noted above, the bubble of secondary fluid can be formed in situ or through an external fluid supply. Further, the in situ bubble can be formed through a chemical reaction, through electrical dissociation of molecules, through heat, or in any other manner. The primary fluid can be any fluid that is to be pumped, such as a liquid or gas. The secondary fluid can be any fluid that presents an interface with the primary fluid having the desired surface tension and other properties. The secondary fluid can be selected based on the primary fluid, the pump structure, and other considerations of each application. Any mechanism can be used to introduce the secondary fluid. In fact, one pump may have different types of mechanisms for introducing the secondary fluid.




The pump can be constructed using standard CMOS compatible semiconductor fabrication techniques or any other techniques. The pump can be formed using a silicon substrate as a body or using any other type of body in which the necessary channels can be formed. The body can be comprised of one or more pieces. The pump can be of any size and the components thereof can have various relative dimensions. Accordingly, the pump can be a microscale pump or a larger or smaller device. The heating elements can be any type of energy delivery device, such as resistive heaters, radiation heaters, convection heaters, heat pumps (such as Peltier coolers), chemical reaction heaters (endothermic or exothermic), nuclear reaction heaters, or the like. The pump can be controlled in any appropriate manner, such as with a microprocessor based device having a predetermined program. The heating elements can be activated to provide a desired temperature gradient in any manner. For example, the heating elements can be controlled by adjusting the current therethrough or by intermittent activation in a predetermined manner. There can be one heating element or plural heating element. The various layers and coatings can be formed using any process and of any materials. The pump can be applied to pumping of various fluids, such as ink in a print head, biological materials, medicaments, or any other fluids.




While the foregoing description includes many details and specificities, it is to be understood that these have been included for purposes of explanation only, and are not to be interpreted as limitations of the present invention. Many modifications to the embodiments described above can be made without departing from the spirit and scope of the invention, as is intended to be encompassed by the following claims and their legal equivalents.















PARTS LIST














Reference No.




Description











 10




Microscale Pump







100




Silicon Substrate







102




First Die







104




Second Die







110




Primary Fluid Channel







120




Primary Fluid Ports







122




Primary Fluid Supply







130




Secondary Fluid Channel







132




External Supply of a Secondary Fluid







140, 142




Thermal Oxide Layer







150, 160




Heating Elements







152, 162




Polysilicon Layer







154, 164




Aluminum Layers







156, 166




Silicon Dioxide Layer







158, 168




Contact Pads







159, 169




Conductor







170




Bubble of Secondary Fluid







171




Photoresist Layer







172




Platinum Layer







174




Oxide Layer







190




Epoxy Layer







200, 300, 400




Microscale Pump







210




Electrodes







220




Bubble







320




Bubble of Secondary fluid














Claims
  • 1. A method for manufacturing a fluid pump comprising the steps of:defining a primary fluid channel in a body; forming a primary fluid aperture in communication with the primary fluid channel; forming a mechanism on the body for introducing a secondary fluid to an interface region of the primary fluid channel; and forming a thermal energy delivery device proximate the interface region, the thermal energy delivery device being adapted to establish a temperature gradient along the interface region of the primary and secondary fluids without boiling of either fluid whereby the primary fluid will move in a direction of decreasing temperature in response to the temperature gradient at the interface region.
  • 2. A method as recited in claim 1, wherein said step of forming a mechanism comprises forming an elongated slot for defining an elongated fluid interface.
  • 3. A method as recited in claim 1, wherein said steps of defining, forming a primary fluid aperture, forming a mechanism, and forming a thermal energy delivery device each comprise performing semiconductor fabrication steps on the body.
  • 4. A method as recited in claim 3, wherein said body comprises first and second dies that are bonded to each other to form the primary fluid channel between them.
  • 5. A method as recited in claim 4, wherein said step of forming an energy delivery device comprises forming a first insulation layer on the first die, forming a doped polysilicon layer on the first insulation layer, forming a conductive layer on the polysilicon layer, patterning the conductive layer into a desired form, patterning the polysilicon layer into resistive elements, and forming a second insulation layer over desired portions of the conductive layer and the polysilicon layer.
  • 6. A method as recited in claim 5, wherein said step of forming a first insulation layer comprises growing a thermal oxide layer on the first die.
  • 7. A method as recited in claim 5, wherein said step of forming a doped polysilicon layer comprises depositing polysilicon on the first insulation layer using an LPCVD process.
  • 8. A method as recited in claim 5, wherein said step of forming a conductive layer comprises sputtering aluminum on the polysilicon layer.
  • 9. A method as recited in claim 5, wherein said steps of patterning the conductive layer and patterning the polysilicon layer each comprise photolithographic etching.
  • 10. A method as recited in claim 5, wherein said step of forming a mechanism comprises forming a secondary fluid channel through said first die.
  • 11. A method as recited in claim 10, wherein said step of forming a primary fluid channel comprises forming a channel pattern in the second die, and attaching the second die to the first die with the channel pattern facing the energy delivery device.
  • 12. A method as recited in claim 5, wherein said step of forming a mechanism comprises forming electrodes proximate the interface region.
  • 13. A method as recited in claim 12, wherein said step of forming a primary fluid channel comprises forming a channel pattern in the second die, and attaching the second die to the first die with the channel pattern facing the energy delivery device.
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