Patent Publication Number: US-6214245-B1

Title: Forming-ink jet nozzle plate layer on a base

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Reference is made to commonly assigned U.S. patent application Ser. No. 09/208,358, filed Dec. 10, 1998, entitled “Fabricating Ink Jet Nozzle Plate,” by Hawkins et al. and U.S. patent application Ser. No. 09/216,523, filed Dec. 18, 1998, entitled “Fabricating Ink Jet Nozzle Plates With Reduced Complexity,” by Hawkins et al. The disclosure of these related applications is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the fabrication of ink jet nozzle plates for ink jet printing apparatus. 
     BACKGROUND OF THE INVENTION 
     Ink jet printing has become a prominent contender in the digital output arena because of its non-impact, low-noise characteristics, and its compatibility with plain paper. Ink jet printing avoids the complications of toner transfers and fixing as in electrophotography and the pressure contact at the printing interface as in thermal resistive printing technologies. Ink jet printing mechanisms includes continuous ink jet or drop-on-demand ink jet. U.S. Pat. No. 3,946,398, which issued to Kyser et al. in 1970, discloses a drop-on-demand ink jet printer which applies a high voltage to a piezoelectric crystal, causing the crystal to bend, applying pressure on an ink reservoir and jetting drops on demand. Piezoelectric ink jet printers can also utilize piezoelectric crystals in push mode, shear mode, and squeeze mode. EP 827 833 A2 and WO 98/08687 disclose a piezoelectric ink jet print apparatus with reduced crosstalk between channels, improved ink protection, and capability of ejecting variable ink drop size. 
     U.S. Pat. No. 4,723,129, issued to Endo, discloses an electrothermal drop-on-demand ink jet printer wherein a power pulse is applied to an electrothermal heater which is in thermal contact with water based ink in a nozzle. The heat from the electrothermal heater can produce a vapor bubble in the ink, which causes an ink drop to be ejected from a small aperture along the edge of the heater substrate. This technology is known as Bubblejet™ (trademark of Canon K.K. of Japan). 
     U.S. Pat. No. 4,460,728, which issued to Vaught et al. in 1982, discloses an electrothermal drop ejection system which also operates by bubble formation to eject drops in a direction normal to the plane of the heater substrate. As used herein, the term “thermal ink jet” refers to both this system and the system commonly known as Bubblejet™. 
     Ink nozzles are an essential component of an ink jet printer, arrays of nozzles being typically provided in an in ink jet nozzle plate. The shapes and dimensions of the ink nozzles strongly affect the properties of the ink drops ejected. For example, it is well known in the art that if the diameter of the ink nozzle opening deviates from the desired size, both the ink drop volume and the velocity can vary from the desired values. In another example, if the opening of an ink nozzle is formed with an irregular shape, the trajectory of the ejected ink drop from that ink nozzle can also deviate from the desired direction (usually normal to the plane of the ink jet nozzle plate). 
     Some known methods of forming ink jet nozzle plates use one or more intermediate molds. One such method uses an electroforming process. The electroforming process uses a mold (or mandrel) overcoated with a continuous conductive film having non-conductive structures that protrude over the conductive film. A metallic ink jet nozzle plate is formed using such a mold (or mandrel) by electroplating onto the conductive film. Over time, the metallic layer grows in thickness. The ink nozzles are defined by the non-conductive structures. One difficulty associated with the above method is the need for the intermediate molds or mandrels. The intermediate molds increase the number of steps in the fabrication process. It is well known in the field of micromachining, that the manufacturing variability increases with the number of the steps in the fabrication process. Since the ink jet nozzle plate comprises structures of small and critical dimensions, it is highly desirable to develop a fabrication process that has fewer number of fabrication steps and does not require the use of intermediate molds or mandrels. 
     A further need for ink jet nozzles in an ink jet printing apparatus is optimization of the nozzle shape. It is well known in the art that the inside surfaces of an ink nozzle can exist in cone, cylindrical, or toroidal shapes with the axis of symmetry generally in the direction of drop ejection. Furthermore, the ink nozzle cross-section perpendicular to the direction of drop ejection can be circular, square or triangular. The structural designs of the ink nozzles can strongly affect the dynamics of the ink fluid during ink drop ejection and refill and therefore determine to a large extent the properties of the ejected ink drops. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide high quality ink jet nozzle plates for use in ink jet printers using manufacturing processes with reduced complexity. 
     Another object is to provide ink jet nozzle plates directly from semiconductor materials without using intermediate molds or mandrels. 
     Yet another object is to provide ink jet nozzle plates with high precision and tolerances using conventional semiconductor fabrication techniques. 
     These objects are achieved by a method for forming an ink jet nozzle plate, comprising the steps of: 
     a) providing a structure having a top substrate layer, a bottom substrate layer, and a buried layer disposed between the top substrate layer and the bottom substrate layer; 
     b) selectively etching the top substrate layer to form a plurality of spaced ink cavities in the top substrate layer exposing portions of the buried layer; 
     c) removing by etching the bottom substrate layer and bonding a base having ink delivery channels over the top substrate layer, with at least one channel corresponding to each ink cavity to thereby form the ink jet nozzle plate; and 
     d) providing a mask having a plurality of openings over the buried layer and etching through such mask openings through the buried layer to the ink cavities to provide at least one bore region corresponding to each ink cavity to provide ink ejection access to such ink cavities so that the buried layer has portions which overhang the ink cavity. 
     ADVANTAGES 
     An advantage of the present invention is that ink jet nozzles for ink jet print heads are effectively provided with simplified micromachining processes. It is particularly advantageous in the manufacture of very small or critically dimensioned ink jet nozzle plates to take advantage of silicon processing technology at all possible steps of the process. 
     A feature of the present invention is that ink jet nozzles are directly fabricated by a method without using one or more intermediate molds. The reduced process complexity permits making very small or critical dimensions for the ink jet nozzle plates. 
     Another feature of the present invention is that an ink jet nozzle plate produced in accordance with the present invention remains protected from particulate contamination during fabrication. 
     A still further feature of the present invention is that silicon nozzle plates can be attached to a variety of non-silicon ink actuators. 
     Another advantage of the present invention is that ink jet nozzles for ink jet print heads are effectively provided with precise tolerances such that the ink drop ejection properties can be optimized. 
     A further advantage of the present invention is that the fabrication methods in the present invention can produce different shapes in the ink nozzle for improved ink drop ejection. 
     Yet a further advantage of the present invention is that an ink nozzle can be formed on a protruded portion of an ink jet nozzle plate for providing mechanical flexibility. 
     A further feature of particular embodiments of the present invention is that the opposing sides of a substrate (or a portion of a substrate) are separately masked and subsequently processed to form an ink jet nozzle plate. The nozzle bore regions and the cavity regions are accurately aligned. The shape and size of the bore and cavity regions can be altered to optimize the performance of the ink drop ejection. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 a - 1   d  are cross-sectional illustrations of a series of steps that are used in practicing the method of the present invention to produce an ink jet nozzle plate in accordance with a first embodiment of the present invention; 
     FIGS. 2 a - 2   f  are cross-sectional illustrations of a series of steps that are used in practicing the method of the present invention to produce an ink jet nozzle plate in accordance with a second embodiment of the present invention; 
     FIGS. 3 a - 3   e  are cross-sectional illustrations of a series of steps that are used in practicing the method of the present invention to produce an ink jet nozzle plate in accordance with a third embodiment of the present invention; 
     FIGS. 4 a - 4   e  are cross-sectional illustrations of a series of steps that are used in a fourth embodiment of the present invention; 
     FIGS. 4 f - 4   i  are cross-sectional illustrations of a series of steps that are used in a modification of the fourth embodiment of the present invention to control surface wetting; 
     FIGS. 5 a - 5   d  illustrate a series of steps that are used in a fifth embodiment of the present invention; 
     FIGS. 6 a - 6   e  illustrate a series of steps that are used in a sixth embodiment of the present invention; 
     FIGS. 7 a - 7   f  illustrate a series of steps that are used in a seventh embodiment of the present invention; and 
     FIGS. 8 a - 8   i  are cross-sectional illustrations of a series of steps that are used in an eighth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is described in relation to the formation of ink jet nozzle plates with very precisely controlled shapes and dimensions without the use of intermediate molds. Specifically, the present invention relates to rapidly and efficiently providing an ink jet nozzle plate from substrates comprised of three layers. 
     The first embodiment of the present invention is shown in FIGS. 1 a - 1   d . A composite substrate  10  comprises a top substrate layer  14 , a buried layer  16 , and a bottom substrate layer  18 . Preferably composite substrate  10  is an SOI (silicon-on-insulator) substrate, commercially available for the manufacture of semiconductor devices, for example high voltage silicon devices, which is well known in the art to have precise top substrate layer dimensions, although other composite substrates may also be used. In this preferred case, the top and bottom substrate layers  14  and  18  are made of silicon material and the buried layer  16  is silicon dioxide. Preferably in the practice of the current invention, the thickness of top substrate layer  14  lies in the range of from 1 to 100 microns and the thickness of buried layer  16  is 0.1 to 10 microns, although other thicknesses may be used as well. As shown in FIG. 1 a , a mask  20  made of photoresist is patterned on top substrate  14  to define openings  20   a  where cavities  12  (shown in FIG. 1 b ) will be formed. A mask made of silicon nitride, deposited for example by low pressure chemical vapor deposition (CVD) and etched with a reactive ion plasma, or of silicon dioxide, made for example by etching a thermal oxide, is also an acceptable mask. In FIG. 1 b , the composite substrate  10  is subject to a wet etch using an anisotropic etchant such as KOH to form cavities  12 . The cavities  12  are defined by inclined walls  14   a  which lie along the [111] crystallographic directions. An area of the buried layer  16  is thereby exposed at the bottom of each cavity  12  after an elapsed time which depends on the thickness of the top substrate layer  14 . The area of the buried layer  16  exposed at the bottom of each cavity  12  is precisely determined because of the precise top substrate layer  14  dimensions and because the etch rates of anisotropic etchants such as KOH in silicon are very low in the crystallographic direction [111] perpendicular to inclined walls  14   a  compared to the vertical direction and because the etch rates of anisotropic etchants such as KOH are very low in the buried layer  16 . 
     Next, as shown in FIG. 1 c , the buried layer  16  at the bottom of cavity  12  is etched from the top side of top substrate layer  14 , preferably by a reactive ion plasma etch which does not etch the material of top substrate layer  14 , to form transfer substrate  30  comprising a plurality of nozzle cavities  34 , having vertical walls  34   a  etched in buried layer  16 . The dimensions of the openings in buried layer  16 , as viewed from the top, are determined only by the areas of the buried layer  16  exposed at the bottom of each cavity  12 , which are precisely controlled as previously described. Because the reactive ion etch does not etch the material of top substrate layer  14 , the inclined wall  14   a  terminates precisely at the edge of vertical wall  34   a . The dimensions of the openings in buried layer  16  and the thickness of this layer will determine the size and shape of the openings in the exit side of nozzle plates made in accordance with this invention, as described below. 
     As shown in FIG. 1 d , a base  50  having ink delivery channels  51  is next bonded to mask  20  by heating the transfer substrate  30  while pressing it in contact with base  50 . Alternatively, mask  20  may be removed by an oxygen plasma and other bonding material applied or bonding can be accomplished by other means, for example by anodic bonding techniques, if the base material is glass or silicon, as is well known in the art. Also as shown in FIG. 1 d , the bottom substrate layer  18  has been removed, for example by wet or dry etching or by grinding, thereby leaving an ink jet nozzle plate  80  bonded to base  50 . The removal of the bottom substrate layer  18  is preferably made by mechanical grinding of a portion of bottom substrate layer  18  followed by chemical polishing or by plasma etching of the remaining portion of bottom substrate layer  18 . Fluorine based etches are particularly suited to removal of silicon material. The ink jet nozzle plate  80  has an exit surface  80   a  with a plurality of openings  84   a  in exit surface  80   a  and a plurality of bore regions  84  through which the ink drops will be ejected. The bore regions  84  are defined in this embodiment by the vertical walls  34   a , by the inclined walls  14   a , and by the patterned mask  20  or other material used in bonding nozzle plate  80  to base  50  In the other embodiments, the bore regions are also those regions through which ink drops will be ejected and are defined by different structures. The precise dimensions provided by this method of nozzle manufacture are advantageous for control of drop size and uniformity in ink jet printing. The use of different materials in the formation of nozzle plates  80  is also advantageous in that it allows control of ink wetting of the exit surface  80   a  as well as meniscus formation and ink refill in the bore regions  84 . The present method is also advantageous in this regard in that the use of different materials in the formation of nozzle plates  80  allows selective removal of one or more of those materials to create precisely modified shapes. The use of different materials in the formation of nozzle plates  80  additionally allows selective surface coatings such as organic surfactants or electroplated surface coatings on one or more of the materials to precisely control the hydrophobicity differences between ink contacting surfaces. 
     FIGS. 2 a - 2   f  illustrate a series of steps to produce an ink jet nozzle plate in accordance with a second embodiment of the present invention. This embodiment allows the formation of openings on the exit surface of a nozzle plate which are located arbitrarily with respect to the nozzle cavities underlying such openings and additionally allows such openings to be of arbitrary shape and number. 
     FIG. 2 a  shows a cross-sectional view of a composite substrate  210  comprised of a top substrate layer  214 , a buried layer  216 , and a bottom substrate layer  218 . Preferably, the composite substrate  210  is a silicon-on-insulator (SOI) substrate, commercially available for the manufacture of semiconductor devices such as high-voltage silicon devices, although other composite substrates may also be used. In an SOI composite substrate, the top substrate layer  214  and the bottom substrate layer  218  are made of silicon and the buried layer  216  is silicon dioxide. 
     As shown in FIG. 2 b , a mask  220  has been provided on the top substrate layer, the mask  220  being preferably silicon dioxide made by growing a thermal oxide, although a mask  220  made of silicon nitride, deposited for example by low pressure chemical vapor deposition (CVD), is also an acceptable mask  220 . The mask  220  is shown patterned, for example by having been coated with a photo-patternable photoresist, and etched. As shown in FIG. 2 b , the top substrate layer  214  of composite substrate  210  has been etched, preferably by a crystallographic wet etch comprising an aqueous mixture of potassium hydroxide (KOH), to form recesses  212 . The recesses  212  are bounded by inclined walls  212   a  and inner surfaces  212   b  which are exposed surfaces of the buried layer  216 . The top substrate layer  214  is thereby modified to become a modified top substrate layer  214   a . As is well known in the art of semiconductor processing with KOH etching, the inclined walls  212   a  lie along [111] planes of the silicon crystal. 
     Next, as shown in FIG. 2 c , modified top substrate layer  214   a  is bonded to a base  250  having ink delivery channels  251 , preferably a flat base, in order to facilitate subsequent photolithography. Many possible means of bonding are known in the art of semiconductor processing. A particularly simple means, appropriate for the manufacture of the present invention, is thermal bonding to a photoresist or other polymer film applied, for example, by spin coating to base  250 . Anodic bonding of oxide to silicon is also a well known process for the provision of secure bonds, although anodic bonds are permanent in nature. In FIG. 2 c , the bonding material has not been shown. Also in FIG. 2 c , mask  220  has been removed, although this step is not required. 
     After base  250  is bonded to modified top substrate layer  214   a , bottom substrate layer  218  is removed. The removal of the bottom substrate layer  218  is preferably made by mechanical grinding and chemical or plasma etching of the silicon material. Fluorine based etches are particularly suited to removal of the silicon material without damage to the silicon dioxide material of buried layer  216 . FIG. 2 c  shows buried layer  216  oriented upwards. After removal of bottom substrate layer  218 , buried layer  216  is coated with a mask  222  patterned with openings  222   a  for subsequent etching. Mask  222  is formed by conventional photolithography on ink jet nozzle plate outer surface  216   a  of buried layer  216  with openings  222   a  centered over inner surfaces  212   b . As is well known in the art of semiconductor manufacture, the alignment between inner surfaces  212   b  and openings  222   a  can be achieved using infra-red photolithography. 
     In FIG. 2 d , buried layer  216  is etched, preferably by reactive plasma etching, to form a modified buried layer  216   b  having a bore region  284  with vertical walls formed in buried layer  216 . The combination of modified buried layer  216   b  and modified top substrate layer  214   a  forms an ink jet nozzle plate  280 . Cavities  286  correspond to the recesses  212  of FIG. 2 b . Bore regions  284  correspond to openings  222   a  in FIG. 2 c . The outer surface of the buried layer  216  is ink jet nozzle plate outer surface  216   a . The modified buried layer  216   b  has portions including the inner surfaces  212   b  which overhang the ink cavities  286 . Because the modified buried layer  216   b  is a different material than modified upper substrate layer  214   a , the interaction of ink with the surfaces of modified buried layer  216   b  is different than the interaction of ink with the surfaces of cavity  286 , depending on the chemical nature of the ink, which is well known to be advantageous in controlling the wetting and refill properties of ink jet nozzle plates. Moreover, because the modified buried layer  216   b  is a different material than modified upper substrate layer  214   a , it is possible to selectively modify the surfaces of modified buried layer  216   b  by chemical treatment to further provide adjustment of the interaction between inks, for example by selectively coating the oxide surfaces of modified buried layer  216   b  with organic surfactants, as is well known in the art of surface modifications, hydrophobic surfaces are formed. Thereby, by applying such modifications selectively to the top side of modified buried layer  216   b , it is possible to provide a top surface of modified buried layer  216   b  which is non-wetting to ink while leaving the cavity side of modified buried layer  216   b  wetting to ink, as is the natural tendency of oxide materials. 
     The ink jet nozzle plate  280  can be used directly on base  250  if base  250  has ink channels  251  so that ink fluids can be supplied to the cavities  286 . In this case, the base  250  may also be processed to include drop actuator structures and ink supply manifolds to provide means of ink drop ejection from bore regions  284 . Common actuator structures for this purpose include piezoelectric actuators and thermal resistive heaters. 
     Alternatively, ink jet nozzle plate  280  may be further processed by the steps of providing a transfer substrate  252  (FIG. 2 e ) which is temporarily bonded to the ink jet nozzle plate outer surface  216   a  of modified buried layer  216   b . The base  250  is then removed from the modified top substrate layer  214   a , by methods similar to those described above for the removal of bottom substrate layer  218  of FIG. 2 b . In this case, base  250  need not have ink channels  251  although base  250  should still be preferably a flat base, in order to facilitate subsequent photolithography. The modified top substrate layer  214   a  is then bonded to a prefabricated ink actuator base  256  (FIG. 2 f ), and the transfer substrate  252  is subsequently removed. The ink actuator base  256  in this case would include the structures for actuating the ejection of ink drops from the bore regions  284 . Such actuator structure can include a thermal electric heater, used in a thermal ink jet print head, or a piezoelectric actuator, as used in a piezoelectric ink jet print head, as is well known in the art. Proper ink channels and manifolds are also included in the ink actuator base  256 . An ink jet nozzle structure  280   a  is thereby provided (FIG. 2 f ). 
     FIGS. 3 a - 3   e  illustrate a series of steps that provide an ink jet nozzle plate in accordance with a third embodiment of the present invention. The nozzle plate is made from a composite substrate having a buried layer as in the previous embodiments but the nozzle plate surface here provided is of a different material from that of the buried layer  216 . In FIGS. 3 a - 3   e , like names correspond to like parts of FIGS. 2 a - 2   e.    
     FIG. 3 a  shows a cross-sectional view of a composite substrate, preferably a silicon-on-insulator (SOI) substrate, processed in a manner identical to that discussed in association with FIGS. 2 a - 2   c  of the present invention except that a nozzle plate overcoat  318  has been deposited uniformly on the top surface of buried layer  216  prior to deposition of mask  222  with openings  222   a . Such a deposited layer may be formed by a variety of thin film deposition techniques, as is well known in the art, and may be comprised of either metals such as titanium or gold or insulators such as silicon nitride, typically used in the manufacture of silicon devices. It is important that either the conductivity of nozzle plate overcoat  318  or the type of etchant that etches nozzle plate overcoat  318  differ from that of buried layer  216 . Next, as depicted in FIG. 3 b , nozzle plate overcoat  318  and buried layer  216  are etched, preferably by a plasma etch, in the regions under the openings  222   a  in mask  222 , to form a bore region  384  in nozzle plate overcoat  318  and buried layer  216  and cavities  286  directly under bore regions  384 . Although the cavities  286  (FIG. 3 b ) of the present embodiment are of the same shape as the cavities  286  of the previous embodiment (FIG. 2 c ), the bore regions  384  (FIG. 3 b ) can be made to differ substantially from the bore regions  284  of FIG. 2 d  due to the presence of nozzle plate overcoat  318 . These differences may include, but are not restricted to, differences in the shapes of the bore region due to the nature of the etches used in forming bore region  384 , and to differences in the relative wetting properties of the nozzle plate overcoat  318  compared to those of buried layer  216  due to the choice of the material for nozzle plate overcoat  318 . 
     The shape of bore region  384  is shown in FIG. 3 b  as a uniform opening with vertical walls, which is the shape formed by using anisotropic etches, such as reactive ion plasma etches, to etch the buried layer  216  and nozzle plate overcoat  318 . This shape, in accordance with the present embodiment, may be altered by further processing. In FIG. 3 c , the shape of the bore region  384  has been altered from that shown in FIG. 3 b  by additionally etching buried layer  216  using an isotropic etch; whereas in FIG. 3 d , the shape of the bore region  384  has been further altered from that shown in FIG. 3 c  by isotropically etching nozzle plate overcoat  318 . In FIG. 3 e , the shape of the bore region has been further altered from that shown in FIG. 3 b  by electrolytic deposition of a nozzle plate overcoat  318 , for example an overcoat of nickel or a nickel alloy. It is possible to electrolytically deposit material selectively if nozzle plate overcoat  318  is a conductor such as a titanium or polysilicon because buried layer  216  is an insulator and therefore the voltage of nozzle plate overcoat  318  may be independently controlled during electrodeposition. As is well known in the art, the ability to alter the shapes and materials in the bore region  384  of ink jet nozzles is advantageous in controlling both the ejection of ink drops and the refilling of ink in cavities  286 . Specifically, the nozzle plate overcoat  318  is preferably nonwetting to the ink fluid so that ink will not flood and form an ink layer on the nozzle plate overcoat  318  during printing. It is well known that an ink layer on the nozzle plate overcoat  318  often causes ink drop ejection to be misdirected and can stop ink ejection altogether. 
     A fourth embodiment of the present invention is shown in FIGS. 4 a  through  4   i  for making very small or critically dimensioned ink jet nozzle plates which are thinner and more flexible than those of the previous embodiments. Masks are used on opposing sides of the ink jet nozzle plate to form cavities and nozzle bores. Although cavities are described for the simple case of inclined walls produced by wet etching, the shape and size of the cavities can be altered by techniques well known to the art of semiconductor etching. 
     FIG. 4 a  shows a composite substrate  430 , comprised of a modified top substrate layer  414   a , a buried layer  416 , and a bottom substrate layer  418 , made identically to the structure discussed in FIG. 2 a . Composite substrate  430  is an SOI (silicon-on-insulator) substrate, commercially available for the manufacture of semiconductor devices, for example high voltage silicon devices, the top and bottom substrate materials of which are silicon and the buried layer  416  of which is silicon dioxide. Modified top substrate layer  414   a  has been formed as in the previous embodiment by etching a first etched region  412 , preferably using a crystallographic wet etch, having an inclined wall  412   a  and a nozzle plate inner surface  412   b  which is an exposed surface of buried layer  416 . Buried layer  416  provides a highly selective etch stop for the etch used to form first etched regions  412 . 
     As shown in FIG. 4 b , after formation of first etched regions  412 , a seed layer  444 , made of a conductive material such as evaporated titanium, copper, or chrome, is uniformly deposited, for example by sputtering or evaporation, over the top surfaces of the structure of FIG. 4 a . Next, an electrolytically deposited plate layer  446 , made of nickel, gold, or metallic alloys, is provided conformally over seed layer  444 , a process well known in the art of electrolytic deposition. Plate layer  446  and seed layer  444  together comprise a nozzle plate layer  445 . As is known in the art, nozzle plate layer  445  can also be deposited by means other than the electrodeposition process described, such as sputter deposition of a single layer, and does not have to be comprised of multiple layers. 
     As shown in FIG. 4 c , a base  450 , optionally having ink delivery channels  451 , is next bonded to top layer  446   a  of plate  446 . A particularly simple means, appropriate for the manufacture of the present invention, is thermal bonding to a polymer film such as a photoresist, which is dissolvable in an organic solvent, applied by spin coating to base  450 . Also as shown in FIG. 4 c , bottom substrate layer  418  has been removed, preferably by mechanical grinding and chemical or plasma etching of the silicon material comprising bottom substrate layer  418 . Fluorine based etches are particularly suited to removal of the silicon material of bottom substrate layer  418  without damage to the silicon oxide material of buried layer  416 . A nozzle plate outer surface  416   a  is thereby formed without loss of the silicon oxide material comprising buried layer  416 . The structure of FIG. 4 c  is shown with nozzle plate outer surface  416   a  oriented upwards. Also as shown in FIG. 4 c , a nozzle mask  422  has been formed by conventional photolithography over nozzle plate outer surface  416   a  having openings  422   a  over nozzle plate inner surfaces  412   b  of FIG. 4 a . Buried layer  416 , plate  446  and seed layer  444  are next etched anisotropically through openings  422   a  (FIG. 4 d ) thereby forming an ink jet nozzle plate  480  having bore regions  484  and cavities  486  in locations corresponding to ink delivery channels  451 . 
     Alternatively, the structure as shown in FIG. 4 b  can be bonded to a first transfer substrate  452  rather than to base  450 , as shown in FIG. 4 e . First transfer substrate  452  need not contain ink delivery channels, but it should be flat and shaped so as to enable conventional photolithography processes to be performed on layers bonded to it. As shown in FIG. 4 e , outer surfaces.  446   a  (FIG. 4 b ) has been bonded to transfer substrate  452  and bottom substrate layer  418  has been removed, preferably by mechanical grinding and chemical or plasma etching of the silicon material comprising bottom substrate layer  418 . A nozzle plate outer surface  416   a  (FIG. 4 c ) is thereby formed without loss of the silicon oxide material comprising buried layer  416 . The structure of FIG. 4 e  is shown with nozzle plate outer surface  416   a  oriented upwards. Also as shown in FIG. 4 e , a nozzle mask  422  has been formed by conventional photolithography over nozzle plate outer surface  416   a  having openings  422   a  located over nozzle plate inner surfaces  412   b  of FIG. 4 a.    
     Buried layer  416 , plate  446  and seed layer  444  are next etched anisotropically through openings  422   a  (FIG. 4 f ) and nozzle plate outer surface  416   a  is bonded to a second transfer substrate  453 . Finally, as shown in FIG. 4 g , surface  446   a  of plate layer  446  is bonded to a base  450  having ink delivery channels  451 , thereby forming an ink jet nozzle plate  480  having bore regions  484  and cavities  486  in locations corresponding to ink delivery channels  451 . This alternative is appropriate when base  450  cannot be easily subjected to conventional photolithographic processing due to reasons of shape, size, or material construction. Bonding of surface  446   a  of plate layer  446  to base  450  may be accomplished by a variety of bonding techniques, an acceptable method in accordance with the present invention being the use of a polymer film which does not dissolve in the solvent capable of dissolving the bonding material used to bond base surface layer  416   a  (FIG. 4 f ) to second transfer substrate  453 . For example, if the material used to bond surface layer  416   a  to first transfer substrate  452  is comprised of water insoluble photoresist, the polymer film used to bond surface  446   a  of plate layer  446  to transfer substrate  453  is preferably a water soluble film such as polyvinyl alcohol, and the preferred means of removing first transfer substrate  452  is immersion in an organic solvent such as acetone which dissolves photoresist, as is well known in the art. 
     As shown in FIG. 4 g , buried layer  416 , modified top substrate layer  414   a  and seed layer  444  may be optionally removed by sequential etching to provide flexible ink jet nozzle plate  480   a . Removal of these layers provides a thin wall ink jet nozzle plate which can be deformed to various degrees depending on the thickness and material of plate  446 . Mechanical flexibility can be advantageous in ink jet printing applications. 
     FIGS. 4 h  and  4   i , with like numbers corresponding to like parts in FIGS. 4 b  and  4   g  respectively, show a nozzle plate made in a manner essentially identical to that of the current embodiment except that an additional outer plate  448  has been deposited immediately after deposition of plate layer  446 . It is understood that the materials for the outer plate  448  can be optimized so that the outer plate  448  is properly passivated for the ink contained in the ink cavity  286 , thereby providing enhanced ink stability. The nozzle plate shown in FIG. 4 i  is comprised of at least two layers. As described previously in the embodiment of FIGS. 3 c - 3   e , a nozzle plate made of more than one layer is advantageous for control of the wetting and refill characteristics of ink in cavities  486  of FIG. 4 i.    
     In a fifth preferred embodiment of the current invention, a nozzle plate is made with a reduced number of process steps; and the nozzle bores are made by etching through the top substrate layer of a composite substrate. Referring now to FIG. 5 a , a composite substrate  510 , comprised of a top substrate layer  514 , a buried layer  516 , and a bottom substrate layer  518  is provided with a photolithographically defined composite mask  523  comprising a bore mask  522  having openings  522   a  and a cavity mask  520  having openings  520   a . Cavity mask  520  is preferably made of silicon nitride and bore mask  522  is preferably photoresist, coated and patterned by conventional lithography after definition of cavity mask  520 . Preferably, composite substrate  510  is an SOI (silicon-on-insulator) substrate. Bore mask  522  defines openings  522   a  for an etched region  534 . As shown in FIG. 5 b , an anisotropic etch is next performed which extends entirely through top substrate layer  514 , buried layer  516 , and a portion of bottom substrate layer  518  having a vertical wall  540 . Thereby top substrate layer  514  is altered to become modified top substrate layer  514   a , buried layer  516  is altered to become modified buried layer  516   a , and bottom substrate layer  518  is altered to become modified bottom substrate layer  518   a . Typically, the layer thickness of the top substrate layer  514 , buried layer  516 , and bottom substrate layer  518  are respectively about 10 microns, 5 microns, and 600 microns respectively and the portion of the etch extending into bottom substrate layer  518  is about 10 microns in depth. However, the thickness are not required to have these values, and more generally may lie in the range of from 2 to 100, 2 to 50, and 200 to 1000 microns respectively, with the portion of the etch extending into bottom substrate layer  518  preferably lying in the range of from 1 to 200 microns. The anisotropic etch is typically a high density reactive ion plasma etch, the gas composition of which is varied as layers of different types are etched, as is well known in the art of semiconductor processing for the preferred materials. 
     As shown in FIG. 5 c , the openings  520   a  (shown in FIG. 5 a ) are substantially wider than the openings  522   a  and are approximately centered over those openings. Referring now to FIG. 5 c , where next, a wet etch is performed, preferably a crystallographic wet etch comprising an aqueous mixture of potassium hydroxide, to form inclined walls  512   a  in a first etched region  512 , thereby altering modified top substrate layer  514   a  to become modified top substrate layer  514   b . As is well known in the art of semiconductor processing, the angles of the inclined walls lie along [111] planes of silicon. Modified top substrate layer  514   b  and modified buried layer  516   a  together comprise an ink jet nozzle plate  580 . At this stage, the ink jet nozzle plate  580  is complete and may be directly bonded to a final device substrate  554  as shown in FIG. 5 d , having ink delivery channels  551 . The final device substrate  554  may be, for example, an ink jet print head of any type. The bonding of inkjet nozzle plate  580  to its desired location may be accomplished by any number of a variety of techniques such as epoxy bonding or metal bonding, as is well known in the art. After bonding to final device substrate  554 , modified bottom substrate layer  518   b  (FIG. 5 c ) may be removed by etching or by a combination of grinding and etching, as is well known in the art of wafer thinning, or the wafer may be thinned by grinding before bonding to the final device substrate. The preferred embodiment in accordance with this advantageously provides an accurately dimensioned nozzle made with a minimal number of processing steps from a composite substrate and able to be transferred simply and directly to a final device substrate. A feature of this embodiment is that lithography is required only on one side of the composite substrate  510 . 
     In a sixth preferred embodiment, an ink jet nozzle plate is made from thin film materials deposited on an SOI composite substrate  630  processed in accordance with the descriptions corresponding to FIGS. 6 a - 6   e . Referring to FIG. 6 a , a composite substrate  630 , comprised of a top substrate layer  614 , a buried layer  616 , and a bottom substrate layer  618  is provided with a photolithographically defined bore mask  622  having openings  622   a , similar to the case of the previous embodiment. Preferably, composite substrate  630  is an SOI substrate, commercially available for the manufacture of semiconductor devices, the top and bottom substrate materials of which are silicon and the buried layer  616  of which is silicon dioxide. Mask  622  is preferable a silicon dioxide mask, made by depositing or growing silicon oxide, coating the oxide with a photo-patternable photoresist, photolithographically defining openings in the photoresist, and then removing by etching the oxide in selected regions to form openings  622   a . As shown in FIG. 6 b , an anisotropic etch is next performed which extends entirely through top substrate layer  614 , buried layer  616 , and a portion of bottom substrate layer  618 , forming bore regions  634 . Thereby top substrate layer  614  is thereby altered to become modified top substrate layer  614   a , buried layer  616  is altered to become modified buried layer  616   a , and bottom substrate layer  618  is altered to become modified bottom substrate layer  618   a . Typically, the layer thicknesses of the top substrate layer  614 , buried layer  616 , and bottom substrate layer  618  are respectively about 10 microns, 5 microns, and  600  microns respectively and the portion of the etch extending into bottom substrate layer  618  is about 10 microns in depth. Layer thickness are not required to have these values, and more generally may lie in the range of from 2 to 100, 2 to 50, and 200 to 1000 microns respectively, with the portion of the etch extending into bottom substrate layer  618  preferably lying in the range of from 1 to 200 microns. The anisotropic etch is typically a high density reactive ion plasma etch, the gas composition of which is varied as layers of different types are etched, as is well known in the art of semiconductor processing for the preferred materials. After etching top substrate layer  614 , buried layer  616 , and a portion of bottom substrate layer  618 , a bore liner layer  640  of a material resistant to wet silicon etching is conformally deposited, for example a 3000 Angstrom layer of silicon nitride may be so deposited by low pressure chemical vapor deposition. Bore liner layer  640  is then etched anisotropically to remove it entirely from horizontally disposed surfaces in FIG. 6 b . It is understood that for some applications, it is desirable to keep the bore liner layer  640  as part of the ink nozzle bore region so that ink meniscus can be pinned at the edge of the bore liner layer  640 . It is well known in the art that pinning ink meniscus at fixed location is desirable for ink ejection reliability. Bore liner  640  may also be made by growing a thermal oxide in bore regions  634  and etching it anisotropically. 
     As shown in FIG. 6 c , mask  622  is removed by etching and a cavity mask  620  having openings  620   a  aligned with openings  622   a  is next provided by using conventional photolithography to define openings in photoresist. Alternatively, cavity mask  620  may be provided as part of a composite mask as described in the previous embodiment (FIG. 5 a ). 
     As shown in FIG. 6 c , the openings  620   a  are substantially wider than the openings  622   a  and are positioned over openings  622   a . Also as shown in FIG. 6 b  and  6   c , the vertical portions of bore liner layer  640  are not substantially etched, as is well known in the art of anisotropic etching. Next, a wet etch is performed, preferably a crystallographic wet etch comprising an aqueous mixture of potassium hydroxide, to form exposed surfaces  614   c  (FIG. 6 d ) in an etched region  612  (FIG. 6 c ), thereby again altering modified top substrate layer  614   a  to become modified top substrate layer  614   b . As is well known in the art of semiconductor processing, the angles of the exposed surfaces  614   c  lie along [111] planes of silicon as shown in FIG. 6 d  where the silicon substrate is of standard [100] orientation. 
     Next, ink jet nozzle plate layer  646 , preferably made of a metal such as gold, is deposited by electrolytic deposition on the exposed surfaces  614   c  (FIG. 6 d ) of modified top substrate  614   b . Any deposition of material on surfaces of modified bottom substrate layer  618   a  can be optionally prevented by electrically biasing modified bottom substrate layer  618   a , as is well known in the art of electrodeposition. To facilitate release of the electrolytically deposited material of ink jet nozzle plate  646 , a thin layer (not shown) of semiconducting carbon can be optionally deposited prior to electrolytic deposition of ink jet nozzle plate layer  646 , for example 100 A of amorphous carbon deposited by plasma decomposition of a hydrocarbon gas such as CH 4 . 
     At this stage, the ink jet nozzle plate layer  646  is complete and may be directly transferred to a final device substrate  654  having ink delivery channels  651 , as shown in FIG. 6 e  After transfer, modified bottom substrate layer  618   a , modified buried layer  616   a , modified top substrate  614   b , and bore liner  640  are removed, for example by wet etching. The final device substrate  654  may be, for example, an ink jet print head channel array, a device know in the art as requiring attached ink jet nozzle plates. The bonding of ink jet nozzle plate layer  646  to its desired location may be accomplished by any number of a variety of techniques such as epoxy bonding or metal bonding, not the subject of the current invention. After bonding to final device substrate  654 , modified bottom substrate layer  618   a  may be removed by etching or by a combination of grinding and etching, as is well known in the art of wafer thinning, or the wafer may be thinned by grinding before bonding to the final device substrate  654 , as shown in FIG. 6 e.    
     The above preferred embodiment advantageously provides very small and accurately dimensioned orifices made from materials such as electrolytically deposited materials which may be transferred simply and directly to a final device substrate. 
     In a seventh preferred embodiment, an ink jet nozzle plate is formed in a simple manner by a process using a buried shadow mask to permit a wide range of deposition conditions for the materials used for the nozzle plate. Referring to FIG. 7 a , a composite substrate  710 , comprising a top substrate layer  714 , a buried layer  716 , and a bottom substrate layer  718 , is provided with a photolithographically defined bore mask  722 , having openings  722   a . As in the case of the previous embodiment, composite substrate  710  is preferably an SOI substrate. As shown in FIG. 7 a , mask  722 , preferably photoresist, is part of a composite mask  723  which includes cavity mask  720  having openings  720   a , similar to the composite mask of the previous embodiment. 
     As shown in FIG. 7 b , an anisotropic etch is next performed which extends entirely through top substrate layer  714 , buried layer  716 , and a portion of bottom substrate layer  718  to form bore etch region  734 . Thereby top substrate layer  714  is altered to become modified top substrate layer  714   a , buried layer  716  is altered to become modified buried layer  716   a , and bottom substrate layer  718  is altered to become modified bottom substrate layer  718   a . Typically, the layer thickness of the top substrate layer  714 , buried layer  716 , and bottom substrate layer  718  generally may lie in the range of from 2 to 100, 2 to 50, and 200 to 1000 microns respectively. The anisotropic etch is typically a high density reactive ion plasma etch, the gas composition of which is varied as layers of different types are etched as is well known in the art of semiconductor processing for the preferred materials. 
     As shown in FIG. 7 c , mask  722  is removed and the cavity mask  720  thereby exposed is used to mask modified top substrate  714   a  so that modified top substrate  714   a  and modified substrate  718   a  can be etched anisotropically to form etched regions  712 . Mask  720 , typically silicon nitride, is provided as part of a composite mask  723  of FIG. 7 a . The etch is preferably a crystallographic wet etch comprising an aqueous mixture of potassium hydroxide, to form inclined walls  712   a  in anisotropically etched region  712 , thereby altering modified top substrate layer  714   a  to become modified top substrate layer  714   b  and altering modified bottom substrate layer  718   a  to become modified bottom substrate layer  718   b . Other etches, such as dry fluorine based plasma etches, are also useful in accordance with the present invention in forming etched regions  712 . Next, as shown in FIG. 7 d  and  7   e  a seed layer  744 , preferably a metal such as nickel or gold, has been deposited, for example by evaporation. A portion of seed layer  744  is horizontally disposed forming a horizontal region  744   e  where the seed layer contacts modified buried substrate  716   a.    
     Modified buried layer  716   a  and modified bottom substrate layer  718   b  act as a buried shadow mask as will be appreciated by one skilled in the art of thin film deposition, separating deposited seed layer  744  into an upper portion  744   a  and a lower portion  744   b , as shown in FIGS. 7 d , and  7   e . Deposition of the seed layer may be preceded by deposition of a thin release layer (not shown) such as oxide or amorphous carbon, as is well known in the art of silicon micromachining. For example,  100  A of amorphous carbon can be deposited by plasma decomposition of a hydrocarbon gas such as CH 4.    
     As shown in FIG. 7 e , if a thicker ink jet nozzle plate is desired, plate layer  746  can be deposited, preferably by electrolytic or electroless deposition, along the exposed surfaces of upper and lower portions  744   a  and  744   b . Any deposition of material on surfaces of lower portion  744   b  can be optionally prevented during electrolytic deposition, since the potential of lower portion  744   b  can be independently controlled during electrolytic deposition, as is well known in the art. By controlling this potential, removal of lower portion  744   b  may also be achieved, as shown in FIG. 7 e . Deposited seed layer  744  alone or in combination with plate material  746 , as shown in FIG. 7 f , comprise ink jet nozzle plate  780 . Seed layer  744  and plate material  746  form a nozzle plate  745  (FIG. 7 e ). However, nozzle plate  745  can also be made as a single layer by a deposition process such as evaporation of an appropriate material such as gold or titanium. 
     At this stage, the ink jet nozzle plate  780  is complete and may be directly transferred to a final device substrate  754  having ink delivery channels  751 , as shown in FIG. 7 f . The final device substrate  754  may be, for example, an ink jet print head channel array, a device known in the art as requiring attached ink jet nozzle plates. The bonding of ink jet nozzle plate  780  to its desired location may be accomplished by any number of a variety of techniques such as epoxy bonding or metal bonding, not the subject of the current invention. After bonding to final device substrate  754 , modified bottom substrate layer  718   b  may be removed by etching or by a combination of grinding and etching, as is well known in the art of wafer thinning, or the wafer may be thinned by grinding before bonding to the final device substrate. 
     The preferred embodiment in accordance with this invention provides very small and accurately dimensioned orifices made from non-silicon processing materials such as electrolytically deposited materials which may be transferred simply and directly to a final device location. 
     In yet another preferred embodiment of the present invention, an ink jet nozzle plate is transferred and bonded to a base with the bore openings of the nozzle plate sealed during the transfer and bonding operation. In accordance with this invention, contamination from particulates is reduced. 
     Referring to FIG. 8 a , a composite substrate  810  has been processed in a manner identical to the process described in association with FIGS. 6 a - 6   c  to form a modified top substrate layer  814   b , a cavity mask  820 , an etched region  812 , a modified buried layer  816   a , a modified bottom substrate layer  818   a , and a bore liner  840 , analogous to modified top substrate layer  614   b , cavity mask  620 , etched region  612 , modified buried layer  616   a , modified bottom substrate layer  618   a , and bore liner  640  of FIG. 6 c . In accordance with the next steps of this embodiment, as shown in FIG. 8 b , cavity mask  820  and bore liner  840  are removed by selective etching, preferably wet etching for the case of bore liner  840  which is preferably made of silicon nitride. The wet etch for silicon nitride does not remove the silicon material of modified top and bottom substrate layers  814   b  and  818   a . Then, as shown in FIG. 8 c , a seed layer  844 , preferably a metal, is deposited over the exposed surfaces of modified top substrate layer  814   b , modified buried layer  816   a , and modified bottom substrate layer  818   a . For example a nickel or gold thin film can be deposited by sputtering. Then a plate layer  846 , preferably a metal, is subsequently deposited, preferably by electrolytic deposition or by electroless deposition. If it is desired to facilitate release of the seed layer  844  and electrolytically deposited plate layer  846 , a thin layer (not shown) of semiconducting carbon can be deposited prior to deposition of seed layer  844 , for example 100 A of amorphous carbon can be deposited by plasma decomposition of a hydrocarbon gas such as CH 4 . Plate layer  846  in combination with seed layer  844  comprise sealed ink jet nozzle plate  870 . It is understood that sealed ink jet nozzle plate  870  is not required to be comprised of more than a single layer and that as an alternative method of fabrication, a single material, for example gold or titanium, could have been deposited by sputtering to form sealed ink jet nozzle plate  870 . 
     At this stage, the sealed ink jet nozzle plate  870  is complete and its top surface may be directly bonded to a base  850  having ink delivery channels  851 , as shown in FIG. 8 d . The bonding of sealed ink jet nozzle plate  870  to base  850  may be accomplished by a variety of well known bonding techniques, such as epoxy bonding or metal bonding, as discussed in previous embodiments. 
     After bonding the top surface of sealed ink jet nozzle plate  870  to base  850 , modified bottom substrate layer  818   a  as well as seed layer  844  and portions of plate layer  846  may be removed entirely or in part by dry or wet etching or by a combination of grinding and dry or wet etching, as shown in FIGS. 8 e - 8   i , to provide nozzle plates of precise geometries and material surfaces. FIGS. 8 e - 8   i  illustrate such methods of processing, in which the sealed ink jet nozzle plate  870  is modified to have nozzle openings, such as nozzle openings  834   a  of FIG. 8 e , through which ink may pass. 
     For example, in FIG. 8 e , modified bottom substrate layer  818   a  is shown removed, for example by grinding followed by chemical mechanical polishing, except for a portion  818   c  of modified bottom substrate layer  818   a  which is not removed. The bottom portion of plate layer  846  and seed layer  844  comprising sealed ink jet nozzle plate  870  is also removed by the grinding and polishing process thereby providing nozzle plate  872   e  having nozzle openings  834   a  through which ink may pass as it flows from ink delivery channels  851 . 
     In a related process, shown In FIG. 8 f , all of modified bottom substrate layer  818   a  and all of modified buried layer  816   a  are shown removed to provide a nozzle plate  872   f  having an extended portion  846   a  extending beyond modified top substrate layer  814   b . Since the plate layer  846  and seed layer  844  are made by thin film deposition techniques, the walls of the extended portion  846   a  are thin, which is advantageous in preventing spreading of ink exiting from the nozzle. 
     In another related process, shown In FIG. 8 g , all of modified bottom substrate layer  818   a , all of modified buried layer  816   a , and seed layer  844  have been removed to provide nozzle plate  872   g , made of a single material. 
     In another related process, shown In FIG. 8 h , only a portion of modified bottom substrate layer  818   a  has been removed leaving a modified bottom substrate layer  818   d . Nozzle plate  872   h  is shown still sealed by end portion  834   b  of sealed ink jet nozzle plate  870  (shown in FIG. 8 c ). Sealing ink jet cavities from the effects of particulate contamination is known to be a useful means of increasing yields and reducing costs of manufacture. In FIG. 8 i , a dry etch has been used to remove the end portion  834   b  of nozzle plate  872   h  of FIG. 8 h  to form nozzle plate  872   i  having a recessed portion  834   c . Such recessed surfaces are known in the art of ink jet nozzle manufacture to be advantageous in controlling the position of the ink meniscus. 
     The preferred embodiment in accordance with this invention a provides very small and accurately dimensioned nozzles which may be transferred to a final location while sealed from particulate contamination, as is well known to be advantageous during assemble processes. 
     The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. 
     PARTS LIST 
       10  composite substrate 
       12  cavity 
       14  top substrate layer 
       14   a  inclined wall 
       16  buried layer 
       18  bottom substrate layer 
       20  mask 
       20   a  opening 
       30  transfer substrate 
       34  nozzle cavity 
       34   a  vertical wall 
       50  base 
       51  ink deliver channel 
       80  ink jet nozzle plate 
       80   a  exit surface 
       84  bore region 
       84   a  opening 
       210  composite substrate 
       212  recess 
       212   a  inclined wall 
       212   b  inner surface 
       214  top substrate layer 
       214   a  modified top substrate layer 
       216  buried layer 
       216   a  ink jet nozzle plate outer surface 
       216   b  modified buried layer 
       218  bottom substrate layer 
       220  mask 
     Parts List (Continued) 
       222  nozzle mask 
       222   a  opening 
       250  base 
       251  ink deliver channel 
       252  transfer substrate 
       256  ink actuator base 
       280  ink jet nozzle plate 
       280   a  ink jet nozzle structure 
       284  bore region 
       286  cavity 
       318  nozzle plate overcoat 
       384  bore region 
       412  first etched region 
       412   a  inclined wall 
       412   b  inner surface 
       414   a  modified top substrate layer 
       416  buried layer 
       416   a  nozzle plate outer surface 
       418  bottom substrate layer 
       422  mask 
       422   a  openings 
       430  composite substrate 
       444  seed layer 
       445  nozzle plate layer 
       446  plate layer 
       446   a  top layer 
       448  outer plate 
       450  base 
     Parts List (Continued) 
       451  ink deliver channel 
       542  first transfer substrate 
       453  second transfer substrate 
       480  ink jet nozzle plate 
       480   a  flexible ink jet nozzle plate 
       484  bore region 
       486  cavity 
       510  composite substrate 
       512  first etched region 
       512   a  inclined walls 
       514  top substrate layer 
       514   a  modified top substrate layer 
       514   b  modified top substrate layer 
       516  buried layer 
       516   a  modified buried layer 
       518  bottom substrate layer 
       518   a  modified bottom substrate layer 
       518   b  modified bottom substrate layer 
       520  cavity mask 
       520   a  opening 
       522  bore mask 
       522   a  opening 
       523  composite mask 
       534  etched region 
       540  vertical wall 
       551  ink deliver channel 
       554  final device substrate 
       580  ink jet nozzle plate 
     Parts List (Continued) 
       612  etched region 
       614  top substrate layer 
       614   a  modified top substrate layer 
       614   b  modified top substrate layer 
       614   c  exposed surface 
       616  buried layer 
       616   a  modified buried layer 
       618  bottom substrate layer 
       618   a  modified bottom substrate layer 
       620  cavity mask 
       620   a  opening 
       622  bore mask 
       622   a  opening 
       630  composite substrate 
       634  bore region 
       640  bore liner layer 
       646  ink jet nozzle plate layer 
       651  ink deliver channel 
       654  final device substrate 
       710  composite substrate 
       712  etched regions 
       712   a  inclined walls 
       714  top substrate layer 
       714   a  modified top substrate layer 
       714   b  modified top substrate layer 
       716  buried layer 
       716   a  modified buried layer 
       718  bottom substrate layer 
     Parts List (Continued) 
       718   a  modified bottom substrate layer 
       718   b  modified bottom substrate layer 
       720  cavity mask 
       720   a  openings 
       722  bore mask 
       722   a  openings 
       723  composite mask 
       734  bore etch region 
       744  seed layer 
       744   a  upper portion 
       744   b  lower portion 
       744   e  horizontal region 
       745  nozzle plate 
       746  plate layer 
       751  ink deliver channel 
       754  final device substrate 
       780  ink jet nozzle plate 
       810  composite substrate 
       812  etched region 
       814   b  modified top substrate layer 
       816   a  modified buried layer 
       818   a  modified bottom substrate layer 
       818   b  modified bottom substrate layer 
       818   c  portion of modified bottom substrate layer 
       818   d  modified bottom substrate layer 
       820  cavity mask 
       834   a  nozzle opening 
       834   b  end portion 
     Parts List (Continued) 
       834   c  recessed portion 
       840  bore liner 
       844  seed layer 
       846  plate layer 
       846   a  extended portion 
       850  base 
       851  ink deliver channel 
       870  sealed ink jet nozzle plate 
       872   e  nozzle plate 
       872   f  nozzle plate 
       872   g  nozzle plate 
       872   h  nozzle plate 
       872   i  nozzle plate