Patent Abstract:
A system ( 10 ) produces patterned deposition on a substrate ( 14 ) from supercritical fluids. A delivery system ( 12 ) cooperates with a partial enclosure environment ( 30, 100, 200 ) retaining a movable substrate ( 14 ) for receiving precipitated functional material ( 44 ) along a fluid delivery path ( 13 ) from the delivery system ( 12 ). A shadow mask ( 22 ) is arranged in close proximity to the movable substrate ( 14 ) for forming the patterned deposition on the movable substrate ( 14 ).

Full Description:
FIELD OF THE INVENTION 
     This invention relates generally to deposition from compressed fluids and, more particularly, to patterned deposition from compressed fluids onto suitable substrates with the use of masks. 
     BACKGROUND OF THE INVENTION 
     Processes that enable patterned deposition of materials onto a substrate have a number of applications, especially in the electronic microcircuit industry. Microfabrication of electronic circuits relies on the ability to create multi-layer patterns of numerous functional materials, with varying electrical properties. The technologies used for creating these multi-layer patterns may be additive, subtractive, or a combination of the two. Additive technologies deposit the functional material on the substrate in the desired pattern, i.e., the pattern is generated directly on the substrate during the deposition/layering process. Subtractive processes, on the other hand, first create a continuous layer of the functional material on the substrate. The desired pattern is then subsequently created by the selective removal of functional material from the deposited layer, i.e., the pattern is created subsequent to the deposition/layering process. A detailed description of various patterned deposition/layering processes used in the microfabrication industry may be found in “Physics of Micro/Nano-Fabrication” by Ivor Brodie and Julius J. Murray, Plenum Press, NY, 1992. 
     Traditional micro-fabrication processes utilize either or both the additive and subtractive processes depending upon the specific application, and are generally carried out in a high vacuum (low-pressure) environment. The high vacuum process generally involves the evaporation of functional material by heating or by ion bombardment followed by deposition onto the substrate by condensation or by a chemical reaction. In these deposition processes, the functional material is required to be thermally stable or to have a thermally stable precursor that can generate the functional material on the substrate by a chemical reaction. As skilled artisans will appreciate, these processes are not useful in generating patterned layers of thermally unstable materials. 
     Further, those skilled in the art will appreciate that it is common to use a mask technique for patterned deposition. Typically, the mask employed for patterning on a planar substrate surface is a photoresist material. However, when the surface is nonplanar, difficulties can be encountered in depositing and cleaning off the photoresist material, necessitating the use of shadow masks or stencils. For example, U.S. Pat. No. 4,218,532 titled “Photolithographic Technique For Depositing Thin Films,” issued Aug. 19, 1980 to Dunkleberger discloses a method for patterned deposition of thin films of metals, such as lead alloys, by vacuum evaporation onto a substrate through openings in a mask fabricated with a predetermined pattern. A shortcoming of this development is that it cannot be used for the patterned deposition of thermally unstable materials since these are not suitable for vacuum evaporation. 
     In U.S. Pat. No. 4,013,502 titled “Stencil Process For High Resolution Pattern Replication,” issued Mar. 22, 1977 to Staples, a process for obtaining high-resolution pattern replication using stencils is disclosed. The stencil in Staples is a mask effecting molecular beam deposition of thin films onto a substrate through openings in the stencil. In this deposition process, the molecular beam source is an electron-beam evaporator. Much like the Dunkleberger development, a shortcoming of Staples&#39; technology is that it cannot be used for patterned deposition of thermally unstable materials that are not suitable for evaporation using an electron beam evaporator. 
     Furthermore, it is well known that patterned deposition of thermally unstable materials on substrates may be achieved by liquid phase processes such as electroplating electrophoresis, sedimentation, or spin coating but these processes are system specific. For example, in the case of electroplating, it is necessary that an electrochemically active solution of the functional material precursor is available. In the case of sedimentation and spin coating, a stable colloidal dispersion is necessary. In the case of electrophoresis, it is also necessary that the stable colloidal dispersion be charged. Microfabrication of multi-layer structures usually requires multiple stages, necessitating the complete removal of residual liquids/solvents at the end of every stage, which can be very energy, time, and cost intensive. Further, many of these liquid-based processes require the use of non-aqueous liquids/solvents, which are hazardous to health and the disposal of which can be prohibitively expensive. For example, in U.S. Pat. No. 5,545,307 titled “Process For Patterned Electroplating,” issued Aug. 13, 1996 to Doss et al., a process is disclosed for patterned electroplating of metals onto a substrate  14  through a mask. The Doss et al. process, however, has at least two major shortcomings. First, it is only applicable to materials that have electrochemically active precursors. Second, it uses an aqueous electroplating bath for the process that requires the coated substrate be cleaned and then dried at the end of the coating process. 
     Moreover, it is well known that to eliminate the need for potentially harmful solvents that need drying, it is possible to use environmental and health-benign supercritical fluids such as carbon dioxide as solvents. For example, in U.S. Pat. No. 4,737,384 titled “Deposition Of Thin Films Using Supercritical Fluids,” issued Apr. 12, 1988 to Murthy et al., a process is disclosed for depositing thin films of materials that are soluble in supercritical fluids onto a substrate. Murthy et al. include the steps of exposing a substrate at supercritical temperatures and pressures to a solution comprising a metal or polymer dissolved in water or a non-polar organic solvent. The metal or polymer is substantially insoluble in the solvent under sub-critical conditions and is substantially soluble in the solvent under supercritical conditions. Reducing the pressure alone, or temperature and pressure together, to sub-critical values cause the deposition of a thin coating of the metal or polymer onto the substrate. Nonetheless, a shortcoming of the process of Murthy et al. is its limited applicability to materials that can be dissolved in compressed fluids, severely limiting the choice of materials that can be deposited on a substrate using this technology. Another shortcoming of the process of Murthy et al. is that it does not teach a process for the patterned deposition of functional materials. 
     In U.S. Pat. No. 4,582,731 titled “Supercritical Fluid Molecular Spray Film Deposition and Powder Formation,” issued Apr. 15, 1986 to Smith, and U.S. Pat. No. 4,734,227 titled “Method Of Making Supercritical Fluid Molecular Spray Films, Powder And Fibers,” issued Mar. 29, 1988 to Smith, independent processes are disclosed for producing solid films on a substrate by dissolving a solid material into supercritical fluid solution at an elevated pressure. In both cases, the supercritical fluid solution is then rapidly expanded in a region of relatively low pressure through a heated nozzle having a relatively short orifice. Both of the aforementioned Smith processes have similar shortcomings to those indicated above, i.e., they are only applicable to materials that are soluble in compressed fluids and do not teach a process for patterned deposition. 
     Therefore, a need persists in the art for a patterned deposition system that permits the patterned deposition of thermally unstable/labile materials and that eliminates the use of expensive and both environmentally and human health-hazardous solvents. A further need exists for a patterned deposition system that eliminates the need for post-deposition drying for solvent-elimination. Moreover, there is an additional need for a patterned deposition technique that is applicable for a wide range of functional materials and that is not limited by specific properties of the functional materials. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the invention to provide a coating deposition system that permits the patterned deposition of thermally unstable/labile materials. 
     Another object of the invention is to provide a coating deposition system that eliminates the need for post-deposition drying for solvent elimination. 
     Yet another object of the invention is to provide a coating deposition system that is applicable for a wide range of functional materials. 
     To achieve these and other objects and advantages of the invention, there is provided, in one aspect of the invention, a system for producing patterned deposition from compressed fluids. The system includes a means for delivering a functional material that is dissolved and/or dispersed in a compressed fluid and then precipitating the functional material by decompressing the compressed fluid to a state where the functional material is no longer soluble and/or dispersible in the compressed fluid. A controlled environment retains a substrate bearing a shadow mask. The controlled environment exposes the substrate bearing the shadow mask to receive precipitated functional material as a patterned deposition on the substrate. 
     There are numerous advantageous effects of the present invention over prior developments. More particularly, the present system has the ability to deposit thermally unstable/labile materials and is useful for a wider range of materials unlike prior art developments. Further, the present system is considerably more efficient and controllable than existing systems. Moreover, the present invention eliminates the need for harmful and expensive materials used for drying. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the detailed description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawings, in which: 
     FIG. 1 is a schematic view of a preferred embodiment made in accordance with the present invention; 
     FIG. 2 is enlarged schematic view of a controlled environment in one embodiment of the invention; 
     FIG. 3 is a schematic view of an alternative embodiment of an enclosure of the invention 
     FIG. 4 is a diagram schematically representing the operation of the present invention; 
     FIG. 5 is a schematic view of an alternative embodiment of a controlled environment or deposition chamber useful in the invention; and, 
     FIG. 6 is a schematic view of an alternative embodiment of another controlled environment or deposition chamber useful in the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the drawings, and more particularly to FIG. 1, system  10 , broadly defined, for producing patterned deposition from compressed fluids includes a delivery system  12 , a deposition chamber, or alternatively controlled environment,  30 , and a substrate  14  retained in the deposition chamber, or alternatively, controlled environment  30 . Controlled environment  30  is more typically a deposition chamber, as described in detail below. A typical delivery system  12  contemplated by the invention is one disclosed, for instance, in commonly assigned in U.S. Patent Application Publication No. 2002/01184245A1 titled “Apparatus And Method Of Delivering A Focused Beam Of A Thermodynamically Stable/Metastable Mixture Of A Function Material In A Dense Fluid Onto A Receiver,” by Ramesh Jagannathan, published Aug. 29, 2002, hereby incorporated herein by reference. Each of the disclosed delivery systems is capable of delivering a precipitate functional material (as described below) and can be used in the invention. 
     Referring to FIG. 1, delivery system  12 , capable of delivering fluids along fluid delivery path  13  in a compressed state, generally includes a source  16  of compressed fluid, a formulation reservoir  18  for containing a formulation material, a discharge assembly  20 , each being described in detail in the above U.S. Patent Applications. Delivery system  12  serves several important functions in the invention. It enables the dissolution and/or dispersal of a selected material into a compressed fluid with density greater than 0.1 g/cc 3 . Further, a solution and/or dispersion of an appropriate functional material or combination of functional materials in the chosen compressed fluid is produced in delivery system  12 . Moreover, delivery system  12  delivers the functional materials as a beam or spray into a deposition chamber  30  in a controlled manner. In this context, the chosen materials taken to a compressed fluid state with a density greater than 0.1 g/cc 3  are gases at ambient pressure and temperature. Ambient conditions are preferably defined as temperature in the range from −100 to +100° C., and pressure in the range from 1×10 −8 -100 atm for this application. 
     As depicted in FIG. 1, controlled environment  30 , such as a deposition chamber, is arranged proximate to delivery system  12 . Controlled environment  30  is positioned at one end of the fluid delivery path  13  and adjacent the discharge assembly  20  of delivery system  12 . As illustrated in FIG. 2, substrate  14  to be patterned with deposition material and is suitably arranged within deposition chamber  30 . In close proximity to substrate  14 , a mask  22  is preferably used (but not required) to control the location of the deposited functional material on the substrate  14 . 
     Referring to FIG. 3, in many applications, it is desirable to maintain an exact concentration of functional material within the controlled enclosure  31 . Whilst open loop systems relying on valve opening times can be used, for greater precision and reliability it is desirable to use a system such as the one illustrated in FIG.  3 . According to FIG. 3, enclosure  31  (applies to enclosures of FIGS. 2,  5  and  6 ) is fitted with at least one viewing window or port  33 . Viewing window  33  can be used alone to provide a visual indication of the conditions inside the enclosure  31 . On the other hand, a viewing window  33  is also required to facilitate the use of optical emitters  35  and optical detectors  37  for the purpose of a more accurate assessment of the concentration of functional material inside the enclosure  31 . The optical emitter  35  emits a beam of light that travels across the inside of the enclosure  31  and is detected by optical detector  37 . This optical detector  37  sends an electrical signal to the microprocessor  39  in proportion to the amount of light received (which is a function of the amount of functional material inside the controlled enclosure  31 ). This information can be used in many ways, most simply as a check of the process, but also as an input to a closed loop control of the input valve  24 . For example, if the concentration in the controlled enclosure  31  is low, the valve  24  is opened allowing more functional material to enter the controlled enclosure  31 . This method relies on the cleanliness of the viewing windows  33  to be effective, and therefore either by routine maintenance, calibration, or the application of a like charge as the particles to the viewing windows  33 , the viewing windows  33  themselves must be kept free of debris. Skilled artisans will appreciate that there are many variations and other detection methods that could be applied to a closed loop concentration monitoring and control method described above. For example, in an optical detection scheme, the optical emitter  35  and optical detector  37  could be on the same side of the controlled enclosure  31  relying on a reflective surface on the opposite side to reflect the beam. The scope is not limited to optical detection, any method that provides an indication of the amount of functional material such as electrical properties, physical properties, or chemical properties could be used. 
     Referring back to FIG. 1, a compressed fluid carrier contained in the source  16  of compressed fluid is any material that dissolves/solubilizes/disperses a functional material. Source  16  of compressed fluids, containing compressed fluid delivers the compressed fluid carrier at predetermined conditions of pressure, temperature, and flow rate as a compressed fluid. Compressed fluids are defined in the context of this application as those fluids that have a density of greater than 0.1 grams per cubic centimeter in the defined range of temperature and pressure of the formulation reservoir, and are gases at ambient temperature and pressure. Materials in their compressed fluid state that exist as gases at ambient conditions find application here because of their unique ability to solubilize and/or disperse functional materials of interest in the compressed fluid state, and precipitate the functional material under ambient conditions. 
     Fluids of interest that may be used to transport the functional material include but are not limited to carbon dioxide, nitrous oxide, ammonia, xenon, ethane, ethylene, propane, propylene, butane, isobutane, chlorotrifluoromethane, monofluoromethane, sulphur hexafluoride, and mixtures thereof. Due to environmental compatibility, low toxicity, low cost, wide availability, and non-flammability, carbon dioxide is generally preferred. 
     Referring again to FIG. 1, formulation reservoir  18  is utilized to dissolve and/or disperse functional materials in compressed liquids or compressed fluids with or without cosolvents and/or dispersants and/or surfactants, at desired formulation conditions of temperature, pressure, volume, and concentration. The formulation may include additives to modify surface tension for charging and wetting viscosity through the use of rheology modifiers and/or thickeners, stabilizers, binders, and dopants. Functional materials may be any material that needs to be delivered to a substrate  14 , for example electroluminescent molecules, imaging dyes, nanoparticles, polymers etc. 
     In addition, the formulation reservoir  18  can include a source that electrically charges the material particles prior to the material being ejected from the discharge assembly  20 . Charging the particles is an important step in many of the preferred embodiments. Alternatively, the marking materials can also be chosen such that the marking material stream becomes charged as it is ejected from the discharge assembly  20  and does not need additional charging. Additionally, additives that can promote charging of the marking materials can also be chosen such that the marking material stream becomes charged as it is ejected from the discharge assembly  20 . Such additives may include surfactants such as those disclosed in U.S. patent application Ser. No. 10/033,458 filed Dec. 27, 2001, titled “A Compressed Fluid Formulation” by Glen C. Irvin, Jr., et al. 
     Further, formulation reservoir  18  can be made out of any suitable materials that can withstand the formulation conditions. An operating range from 0.001 atmospheres (1.013×10 2  Pa) to 1000 atmospheres (1.013×10 8  Pa) in pressure and from −25° Centigrade to 1000° Centigrade is preferred. Typically, the preferred materials of construction include various grades of high pressure stainless steel. However, the material of choice is determined by temperature and pressure range of operation. 
     Formulation reservoir  18  should be precisely controlled with respect to the operating conditions, i.e., pressure, temperature, and volume. The solubility/dispersability of functional materials depends upon the conditions within the formulation reservoir  18  and even small changes in the operating conditions within the formulation reservoir  18  can have undesired effects on functional material solubility/dispersability. 
     Any suitable surfactant and dispersant material that is capable of solubilizing/dispersing the functional materials in the compressed liquid for the required application can be used in this method. Such materials include but are not limited to fluorinated polymers such as perfluoropolyether and silane and siloxane compounds. 
     Referring to FIGS. 1 and 4, delivery system  12  is shown in fluid communication through orifices/nozzles  28  with enclosed, controlled environment  30  that contains substrate  14  and mask  22 . According to FIG. 1, valve  24  may be designed to actuate with a specific frequency or for a fixed time period so as to permit the controlled release of formulation from formulation reservoir  18  into enclosed environment  30  via orifices/nozzles  28 . According to FIG. 4, the controlled release of functional material  40  into enclosed environment  30  results in the evaporation of the compressed fluid  41  and the precipitation and/or aggregation of the dissolved and/or dispersed functional material  40 . The precipitated/aggregated functional material may be allowed to gravity-settle or may be settled using an electric, electrostatic, electromagnetic, or magnetic assist. Mask  22  in close proximity to substrate  14  results in the patterned deposition of functional material  40  on the substrate  14 . 
     Substrate  14  may be any solid including an organic, an inorganic, a metallo-organic, a metallic, an alloy, a ceramic, a synthetic and/or natural polymeric, a gel, a glass, and a composite material. Substrate  14  may be porous or non-porous. Additionally, the substrate  14  can have more than one layer. Additionally, the substrate  14  may be flexible or rigid. 
     As best illustrated in FIGS. 2 and 4, mask  22  may be physical (separate) or integral. The purpose of the mask  22  is to provide a pattern for the deposition of functional solute material. Those skilled in the art will appreciate that mask design and manufacture is well established. Physical masks require direct contact between mask  22  and substrate  14 . Their advantage is that they are relatively inexpensive and can be re-used for multiple substrates  14 . However, if the substrate  14  is delicate, the physical contact may damage the substrate  14 . Precise alignment is also difficult. Integral masks  22  are structures formed on the substrate  14  prior to coating/deposition. Alignment and spacing is easier because the mask  22  is a part of the substrate  14 . However, because of the potential need to remove the mask  22  after deposition, a subsequent etching step may be necessary, potentially making this more expensive and time-consuming. 
     Referring to FIG. 4, nozzle  28  directs the flow of the functional material  40  from formulation reservoir  18  via delivery system  12  into enclosed environment  30 . Nozzle  28  is also used to attenuate the final velocity with which the functional material  40  enters the enclosed environment  30 . In our preferred application, it is desirable to rapidly spread the stream of precipitated functional material  40  using a divergent nozzle geometry. Skilled artisans will however appreciate that nozzle geometry can vary depending on a particular application, as described in U.S. Patent Application Publication No. 2002/011842A1, incorporate herein by reference. 
     In Operations 
     Operation of system  10  will now be described. FIG. 4 is a diagram schematically representing the operation of delivery system  10  and should not be considered as limiting the scope of the invention in any manner. The description below uses a single nozzle  28  although multiple nozzles and/or multiple nozzle shapes and/or multiple delivery devices and shapes are within the contemplation of the invention. (See for instance other nozzle exemplars disclosed in U.S. Patent Application Publication No. 2002/0118245A1. 
     Referring to FIG. 4, a formulation  42  of functional material  40  in a compressed liquid  41  is prepared in the formulation reservoir  18  of the invention. Functional material  40 , which may be any material of interest in solid or liquid phase, can be dispersed (as shown in FIG. 4) and/or dissolved in a supercritical fluid and/or compressed liquid  41  making a mixture or formulation  42 . Functional material  40  may have various shapes and sizes depending on the type of the functional material  40  used in the formulation. 
     According to FIG. 4, the supercritical fluid and/or compressed liquid  41  form a continuous phase and functional material  40  forms a dispersed and/or dissolved single phase. The formulation  42  (i.e., the functional material  40  and the supercritical fluid and/or compressed liquid  41 ) is maintained at a suitable temperature and a suitable pressure for the functional material  40  and the supercritical fluid and/or compressed liquid  41  used in a particular application. The shutter  32  is actuated to enable the ejection of a controlled quantity of the formulation  42 . 
     With reference to FIGS. 1 and 4, functional material  40  is controllably introduced into the formulation reservoir  18 . The compressed fluid  41  is also controllably introduced into the formulation reservoir  18 . The contents of the formulation reservoir  18  are suitably mixed using a mixing device (not shown) to ensure intimate contact between the functional material  40  and compressed fluid  41 . As the mixing process proceeds, functional material  40  is dissolved and/or dispersed within the compressed fluid  41 . The process of dissolution/dispersion, including the amount of functional material  40  and the rate at which the mixing proceeds, depends upon the functional material  40  itself, the particle size and particle size distribution of the functional material  40  (if the functional material  40  is a solid), the compressed fluid  41  used, the temperature, and the pressure within the formulation reservoir  18 . When the mixing process is complete, the mixture or formulation  42  of functional material and compressed fluid is thermodynamically stable/metastable in that the functional material is dissolved or dispersed within the compressed fluid in such a fashion as to be indefinitely contained in the same state as long as the temperature and pressure within the formulation reservoir  18  are maintained constant or in the same state for the period of the efficient operation of the process (metastable). This thermodynamically stable state is distinguished from other physical mixtures in that there is no settling, precipitation, and/or agglomeration of functional material particles within the formulation reservoir  18  unless the thermodynamic conditions of temperature and pressure within the formulation reservoir  18  are changed. As such, the functional material  40  and compressed fluid  41  mixtures or formulations  42  of the present invention are said to be thermodynamically stable. 
     The functional material  40  can be a solid or a liquid. Additionally, the functional material  40  can be an organic molecule, a polymer molecule, a metallo-organic molecule, an inorganic molecule, an organic nanoparticle, a polymer nanoparticle, a metallo-organic nanoparticle, an inorganic nanoparticle, an organic microparticle, a polymer micro-particle, a metallo-organic microparticle, an inorganic microparticle, and/or composites of these materials, etc. After suitable mixing with the compressed fluid  41  within the formulation reservoir  18 , the functional material  40  is uniformly distributed within a thermodynamically stable/metastable mixture, that can be a solution or a dispersion, with the compressed fluid  41 . This thermodynamically stable/metastable mixture or formulation  42  is controllably released from the formulation reservoir  18  through the discharge assembly  20 . 
     Referring again to FIG. 4, during the discharge process, the functional material  40  is precipitated from the compressed fluid  41  as the temperature and/or pressure conditions change. The precipitated functional material  44  is ejected into the deposition chamber or controlled environment  30  by the discharge assembly  20 . The particle size of the functional material  40  ejected into the chamber  30  and subsequently deposited on the substrate  14  is typically in the range from 1 nanometer to 1000 nanometers. The particle size distribution may be controlled to be more uniform by controlling the formulation (functional solute materials and their concentrations) rate of change of temperature and/or pressure in the discharge assembly  20 , and the ambient conditions inside the controlled environment  30 . 
     Although not specifically shown, delivery system  12  (FIG.  4 ), contemplated by the invention, is also designed to appropriately change the temperature and pressure of the formulation  42  to permit a controlled precipitation and/or aggregation of the functional material  40  (see for instance U.S. Patent Application Publication No. 2002/0118245A1). As the pressure is typically stepped down in stages, the formulation  42  fluid flow is self-energized. Subsequent changes to the conditions of formulation  42 , for instance, a change in pressure, a change in temperature, etc., result in the precipitation and/or aggregation of the functional material  40  coupled with an evaporation of the compressed fluid  41 . The resulting precipitated and/or aggregated functional material  44  deposits on the substrate  14  evenly. According to FIG. 4, evaporation of the compressed fluid  41  can occur in a region located outside of the discharge assembly  20  within deposition chamber  30 . Alternatively, evaporation of the compressed fluid  41  can begin within the discharge assembly  20  and continue in the region located outside the discharge assembly  20  but within deposition chamber  30 . Alternatively, evaporation can occur within the discharge assembly  20 . 
     According to FIG. 4, a stream  43  of the functional material  40  and the compressed fluid  41  is formed as the formulation  42  moves through the discharge assembly  20 . When the size of the stream  43  of precipitated and/or aggregated functional material  44  is substantially equal to an exit diameter of the nozzle  28  of the discharge assembly  20 , the stream  43  of precipitated and/or aggregated functional material  44  has been collimated by the nozzle  28 . When the size of the stream  43  of precipitated and/or aggregated functional material  44  is less than the exit diameter of the nozzle  28  of the discharge assembly  20 , the stream  43  of precipitated and/or aggregated functional material  44  has been focused by the nozzle  28 . It may be desirable for a deposition chamber input to be a diverging beam to quickly spread the precipitated and/or aggregated functional material  44  and dissipate its kinetic energy. Such an input is possible without a nozzle  28 . 
     Referring again to FIGS. 2,  4  &amp;  5 , substrate  14  resides within deposition chamber  30  such that the stream  43  of precipitated and/or aggregated functional material stream  44  is deposited onto the substrate  14 . The distance of the substrate  14  from the discharge assembly  20  is chosen such that the compressed fluid  41  evaporates prior to reaching the substrate  14 . Hence, there is no need for subsequent substrate  14  drying processes. Further, subsequent to the ejection of the formulation  42  from the nozzle  28  and the precipitation of the functional material  44 , additional focusing and/or collimation may be achieved using external devices such as electromagnetic fields, mechanical shields, magnetic lenses, electrostatic lenses, etc. Alternatively, the substrate  14  can be electrically or electrostatically charged such that the position of the functional material  40  can be controlled. 
     Referring again to FIG. 4, it is also desirable to control the velocity with which individual particles  46  of functional material  40  are ejected from the nozzle  28 . Since there may be a sizable pressure drop from within the delivery system  10  to the operating environment, the pressure differential converts the potential energy of the delivery system  10  into kinetic energy that propels the functional material particles  46  onto the substrate  14 . The velocity of these particles  46  can be controlled by suitable nozzle design (see discussion above) and by controlling the rate of change of operating pressure and temperature within the system. Further, subsequent to the ejection of the formulation  42  from nozzle  28  and the precipitation of the functional material  40 , additional velocity regulation of the functional material  40  may be achieved using external devices such as electromagnetic fields, mechanical shields, magnetic lenses, electrostatic lenses, etc. The nozzle design will depend upon the particular application addressed. (See, for instance, U.S. Patent Application Publication No. 2002/0118245A1). 
     Moreover, the temperature of nozzle  28  may also be controlled. Referring to FIG. 4, the temperature of nozzle  28  may be controlled as required by specific applications to ensure that the nozzle opening  47  maintains the desired fluid flow characteristics. Nozzle temperature can be controlled through the nozzle heating module (not shown) using a waterjacket, electrical heating techniques, etc. (See, for instance, U.S. Patent Application Publication No. 2002/0118245A1). With appropriate nozzle design, the exiting stream temperature can be controlled at a desired value by enveloping the exiting stream with a co-current annular stream of a warm or cool inert gas. 
     Embodiment I 
     Referring to FIG. 2, controlled environment  30  is designed for use at extremes of pressure. Incorporated in the controlled environment  30  is a pressure modulator  105 . The pressure modulator  105 , as shown, resembles a piston. This is for illustration only. Skilled artisans will also appreciate that pressure modulator  105  could also be a pump or a vent used in conjunction with an additional pressure source. An example of an additional pressure source is the source  109  of compressed fluid. This source  109  is modulated with a flow control device or valve  108  to enable functional material to enter the deposition chamber  30  via a fluid delivery path  13 . The pressure inside the deposition chamber  30  is carefully monitored by a pressure sensor  103  and can be set at any pressure less than that of the delivery system  12  (including levels of vacuum) to facilitate precipitation/aggregation. In addition, the deposition chamber  30  is provided with temperature sensor  104  and temperature modulator  106 . Temperature modulator  106  is shown as an electric heater but could consist of any of the following (not shown): heater, a waterjacket, a refrigeration coil, and a combination of temperature control devices. 
     Referring to FIGS. 1,  2 , and  4 , deposition chamber  30  generally serves to hold the substrate  14  and the mask  22  and facilitates the deposition of the precipitated functional material  44 . To enable a more complete and even distribution of the functional material  40 , electric or electrostatic charges can be applied to the substrate  14  and/or mask  22 . Through the ejection process in the discharge assembly  20 , the particles are known to become charged. If desired, additional charge can be applied to them using a particle charging device  107  (FIG.  2 ). The functional material  40 , now charged can be attracted or repelled from various surfaces to aid in the deposition process. According to FIG. 2, charging devices  102   a ,  102   b  are provided for both the substrate  14  and mask  22 , respectively. For illustrative purposes only, a positive charge (+) is shown on substrate  14  and a negative charge (−) is shown on mask  22 . The polarity may be changed to suit the application. A charge equal to that of the functional material  40  is applied to the mask  22 , whereas a charge opposite of that of the functional material  40  is applied to the substrate  14  to attract the functional material. Obviously there can be no electrical conduction between the two to maintain the charge differential. This may limit the material selection of one or both, or add the requirement for an additional insulating layer (not shown). In a similar manner, it may be beneficial to create other electric or electrostatic charges on the deposition chamber  30  or on any other mechanical elements within the deposition chamber  30 . As shown in FIG. 6, an internal baffle  122  may be used to provide a more even distribution of functional material  40  within the deposition chamber  200 . A charge may be applied to the internal baffling by a baffle charging device  123 . 
     Referring again to FIG. 2, deposition chamber  30  also provides easy access for the insertion and removal of the substrate  14  through access port  101 . This process will potentially be automated by mechanical devices which are not shown. Access port  101  of deposition chamber  30  also provides access for the insertion and removal of the mask  22  as well as for the proper placement of the mask  22 . Mask alignment relative to the substrate  14  is key to this application and may be manual or preferably, automated. Though it is shown oriented with the substrate  14  facing upwards, this is not a requirement of the invention. When attracting particles electrostatically, it may be advantageous to orient the substrate  14  facing downward. In this manner, no debris from the deposition chamber  30  could inadvertently fall onto the substrate  14 . 
     The controlled environment can be used for post deposition processing of the deposited material on the substrate. Post deposition processing may involve the control of humidity, temperature, atmospheric conditions including pressure, and chemical composition of the atmosphere. As an example, many processes require the curing of the materials to obtain desired functionality at elevated temperature. The thermal control that is already built into the enclosure can be utilized for this purpose. Alternatively, the post processing required can be done outside the enclosure. 
     It should be appreciated that deposition chamber  30  should also be designed so that there are no dead volumes that may result in the accumulation of precipitated functional materials  44  and so that it may be easily cleaned. As such, it may be further partitioned into more than one sub-chamber to facilitate the above (not shown). It may also be equipped with suitable mechanical devices to aid the precipitation and deposition of functional material  40 . An example of such a device would be a mechanical agitator. 
     Embodiment II 
     Turning now to FIG. 5, another embodiment of deposition chamber  100 , contemplated by the invention, is shown. It contains many of the same features previously described in the discussion of FIG. 2, with the addition of a medium  111  which divides the deposition chamber  100  into a preparation sub-chamber  100   a , and a deposition sub-chamber  100   b . The materials in these sub-chambers  100   a ,  100   b  are allowed to flow through controllable dual chamber interface valve  110 . Each sub-chamber  100   a ,  100   b  is configured with independent control of pressure and temperature through the use of pressure sensors  103 , temperature sensors  104 , pressure modulators  105 , and temperature modulators  106 . The preparation sub-chamber  100   a  differs from the formulation reservoir  18  (FIG. 1) in that the functional material  40  can be (but is not necessarily) precipitated. The addition of a preparation sub-chamber  100   a  to the system allows for a potentially large volume of prepared deposition material to be ready and maintained at a higher than ambient pressure while still allowing the changing of substrate  14  and deposition material through the access port  101 . 
     Embodiment III 
     In FIG. 6, a simplified deposition chamber  200  is illustrated. In this embodiment, no provision is made for maintaining a pressure above that of ambient. Many of the other features described in FIGS. 2 and 5 are still possible, but by no longer requiring the deposition chamber  200  to support an elevated pressure, certain additional advantages can be realized. For example, the substrate  14  no longer is required to be contained in deposition chamber  200 . This is illustrated in FIG. 6 by showing a moving substrate in the form of a web  120  that is transported by conveyors  121 . In such a system, it is possible to perform continuous coating operations. In this case, a separate mask would likely not be used except for the case of a step and repeat process. Rather, a mask integral to the substrate, as previously described, is the preferred method of achieving patterned deposition. Alternatively, a similar approach, illustrated in FIGS. 2 and 5, could be used also without need for access port  101 . 
     Additional aspects of the invention may include multiple deposition chambers  30 ,  100 , or  200 , as illustrated in FIGS. 2,  5 , and  6 , for coating multiple layers onto substrate  14 . Alternatively, multiple masks  22  may be used such that a mask with a specific configurational structure of aperture patterns is used and subsequently replaced with another shadow mask of different configurational structure of aperture patterns on the same substrate  14 . Multiple masks, indexing of a mask, multiple layers, and multiple material processes are commonly used in the manufacture of displays, therefore details and methods to provide proper registration such as through the use of optical fiducials are well known. The sequential process used for deposition of colored material(s) for display products applications may be interspersed with other processes, including deposition of other material(s) and/or post treatment of deposited material(s), as needed, to create a desired product. 
     It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art. Additionally, materials identified as suitable for various facets of the invention, for example, functional materials. These are to be treated as exemplary, and are not intended to limit the scope of the invention in any manner. 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 10 
                 system 
               
               
                 12 
                 delivery system 
               
               
                 13 
                 fluid delivery path 
               
               
                 14 
                 substrate 
               
               
                 16 
                 source of compressed fluid 
               
               
                 18 
                 formulation reservoir 
               
               
                 20 
                 discharge assembly 
               
               
                 22 
                 mask 
               
               
                 24 
                 closed loop control of the input valve 
               
               
                 28 
                 orifices/nozzles 
               
               
                 30 
                 deposition chamber or controlled environment 
               
               
                 31 
                 enclosure 
               
               
                 32 
                 shutter 
               
               
                 33 
                 viewing window 
               
               
                 35 
                 optical emitter 
               
               
                 37 
                 optical detector 
               
               
                 39 
                 microprocessor 
               
               
                 40 
                 functional material 
               
               
                 41 
                 compressed fluids 
               
               
                 42 
                 formulation of functional material 40 
               
               
                 43 
                 stream of functional material 40 
               
               
                 44 
                 precipitated and/or aggregated functional material 
               
               
                 46 
                 functional material particles 
               
               
                 47 
                 nozzle opening 
               
               
                 100 
                 alternative embodiment of deposition chamber or controlled 
               
               
                   
                 environment 
               
               
                 100a 
                 preparation sub-chamber 
               
               
                 100b 
                 deposition sub-chamber 
               
               
                 101 
                 access port 
               
               
                 103 
                 pressure sensor 
               
               
                 102a 
                 charging device 
               
               
                 102b 
                 charging device 
               
               
                 104 
                 temperature sensor 
               
               
                 105 
                 pressure modulator 
               
               
                 106 
                 Temperature Modulator 
               
               
                 107 
                 particle charging device 
               
               
                 108 
                 flow control valve 
               
               
                 109 
                 source of compressed fluids 
               
               
                 110 
                 interface valve 
               
               
                 111 
                 medium 
               
               
                 120 
                 web 
               
               
                 121 
                 conveyor 
               
               
                 122 
                 internal baffle 
               
               
                 123 
                 baffle charging device 
               
               
                 200 
                 another alternative embodiment of deposition chamber 
               
               
                   
                 or controlled environment

Technology Classification (CPC): 1