WO1995013566A1

WO1995013566A1 - Method for back-side photo-induced ablation for making a color filter, or the like

Info

Publication number: WO1995013566A1
Application number: PCT/US1994/012991
Authority: WO
Inventors: Sheau-Sheng Chen; Theodore Huu Dang; Hongye Sun
Original assignee: Xmr, Inc.
Priority date: 1993-11-10
Filing date: 1994-11-10
Publication date: 1995-05-18

Abstract

A method of back-side photo-induced ablation, in which a laser is directed through a mask at the back side of a light-transmissive substrate, and the ablated areas are then filled with a filling material. This technique may be used as a method of making color filters, by repeatedly ablating different areas and filling with different colored filling materials.

Description

METHOD FOR BACK-SIDE

PHOTO-INDUCED ABLATION

FOR MAKING A COLOR FILTER, OR THE LIKE

Field of the Invention

The field of the invention relates generally to a method for high resolution, energy efficient ablation. More particularly, the field of the invention relates to a method of back-side photo-induced ablation, whereby material may be ablated from the surface of a light transmissive substrate by irradiating the material through the substrate. The method may be used to ablate a wide variety of materials for processing such things as semiconductor devices or the like; however, the present invention is especially applicable to the making of a color filter. Color filters for display devices, or the like now can be made with few processing steps and at submicron resolution. The invention also makes possible the fabrication of color filters with high edge definition.

Background Photo-induced ablation has a wide variety of uses for efficient, high resolution removal of materials for such things as semiconductor and microelectronic processing. In particular, it has application for the development of color filters. Large flat panel displays using liquid crystals and switched by individual thin film silicon transistors are being produced in limited quantities and are expected to achieve a market size paralleling IC production. These large displays have application in laptop computers, dedicated work processors and flat screen and projection television systems. Full color displays are now entering production, requiring color filter material.

The color filter fabrication process is the first step in the manufacture of color LCD displays and includes the deposition and patterning of the color filter elements. Types of color filters for LCDs are either dyestuff or pigment. Each color filter element includes three primary color elements—red, green and blue (RGB)—and a black border for contrast. Other color combinations are possible, such as an RGGB quad color matrix or Cyan, Yellow, and Magenta. A conventional primary color element may be about 100 X 300 microns in size. Resolution is limited by the size and edge definition of the color filter elements. The traditional photolithographic techniques for deposition and patterning of these color filter elements require lengthy, toxic and expensive processes resulting in low yields and barely acceptable performance. Conventional contact printing, using a photolithographic process, requires a minimum of eight (8) steps per color layer, for three color layers plus black, totaling thirty-two (32) different steps to lay down the color. The steps in making the color filter include bare glass processing, wash and clean, drying, undercoat, cure, color filter formation, overcoat, and cure. Color filter formation is accomplished by photolithographic processes, screen and offset printing, or electrodeposition. Resolutions of approximately 10-20 microns may be obtained by such conventional methods. The traditional photolithographic method coats the substrate (typically glass) with a polyimide color filter material which is dried. Three key materials used to pattern the polyimide, (the positive photoresist, a rapid-drying solvent and the developer) , are all toxic, are all expensive and difficult to discard as wastes. These materials are used on each of the four layers. Thus, the number of process steps, and cost and toxicity of chemicals used are serious disadvantages of traditional methods. In addition, the use of chemicals to form color filter elements causes undercutting whereby the chemicals etch beneath any mask elements into adjacent areas of filter material. This limits resolution, which is another disadvantage of traditional techniques.

To overcome the above disadvantages, laser ablation has been explored as a technique to form filter elements. The basis of the technique is the process of ablative photodecomposition, which is well-known in the art. When any photoablative material is exposed to laser light with sufficient photon energy flux, it undergoes a transition -to the gas phase, so suddenly that the thermal effect on the surrounding material is minimal. This has also been described as a photochemical decomposition that is brought about by a multiphoton excitation process to a high electronic state (R. Srinivasan, B. Braren, and R.W. Dreyfus, J. Appl. Phys. 61(1), 372 (1987)). Srinivasan teaches that the conventional laser ablation process must involve many photons per monomer unit to account for the production of predominantly small (<4 atoms) products and the ejection of these fragments at supersonic velocities.

Conventional laser ablation may be used to form pixel holes in black filter material. Primary color elements can then be deposited into the pixel holes and cured. It is desirable to obtain high resolution with such a process, but without resorting to the high energy and cost requirements of X-ray lithography.

Research in this area shows that excimer lasers can be used to etch and ablate a variety of materials. Excimer lasers have been used to pattern complex lines of polyvinylidene difluoride as narrow as 20 microns

(M. Gauthier, R. Bourret, C. Jen and E. Adler, Mat. Res. Soc. Sy p. Processes on Surfaces, 399 (Nov.-Dec. 1988)). Photoetching of a number of polymeric materials including poly(methyl-methacrylate) (PMMA) , poly vinylacetate (PVA) , poly (a-methyl styrene) (PS) , poly (tetrafluoroethylene) (PTFE) , polyproylene (PP) , nitrocellulose, copolymer styrene allyl alcohol (SAA) and polymer-monomer mixture PVA plus 25% wt biphenyl carbonitrile has also been measured (Y.S. Liu, H.S. Cole, H.R. Phillip, and R. Guida, SPIE Vol. 774, Lasers in Microlithography, 133-136 (1987)). And polyimide films of Dupont Kapton have been etched by laser ablation through photochemical decomposition (R. Srinivasan, B. Braren, and R.W. Dreyfus, J. Appl. Phys. 61(1), 372 (1987)) . Rates of photoetching are dependent upon the optical energy absorption coefficient and chemical structures of the ablative material.

However, traditional methods of excimer laser ablation—channeling the laser through a mask directly onto the material to be ablated (front side laser ablation) —has serious drawbacks, particularly when applied to color filter materials such as polyimide. The ablated material is vaporized and ejected from the top of the filter material. This causes splattering of fragments within the ablated area and on adjacent areas, reducing resolution. Resolution of only about 7 or 8 microns has been obtained with conventional front side laser ablation. In addition, the vaporized material scatters and absorbs laser light, increasing the energy and number of laser pulses needed to remove the remaining filter material. This effect increases as the size of the ablated area increases. A complex and expensive vacuum system or nitrogen purging system is necessary to remove this material during ablation.

Also, the vaporized material is in an excited state, having absorbed energy from the laser. This material is ejected from the surface and the energy is lost from the system. It would be advantageous to use the energy in this material for further ablation, until all the desired material has been ablated.

In addition, the vaporization and ejectment of material may damage the mask which may be as close as a few microns to the ablative material. Further, the masks must be painstakingly aligned with the material to be ablated, and any accidental contact with the mask during this process may damage it. These masks are very expensive and represent a significant portion of the cost of laser ablation processes.

What is needed is a method of ablation, for fabricating color filters or the like, with the capability of achieving submicron resolution and strong edge definition. This resolution has not been obtained using traditional photolithographic or excimer laser ablation processes. The desired method should not require the costly process steps and toxic chemicals required for traditional photolithographic processes. In addition, it should not cause splattering or damage to masks as with front side laser ablation. It is also desirable that such a method allow the use of a contact mask to reduce alignment problems and decrease the risk of damage to the mask.

What is also needed is an improved method of ablation for achieving submicron resolution, on the order of .3 microns and smaller, without resorting to the high energy requirements or capital cost of X-ray lithography. Preferably such a method would require less energy than even conventional front side excimer laser ablation.

Summary of the Invention

In order to overcome the above-discussed disadvantages of known methods of semiconductor processing for fabricating a color filter or the like, an aspect of the present invention provides a method for using radiant energy applied to the back side of a light transmissive substrate to remove an ablative material from the front side of the substrate.

In accordance with an aspect of the present invention, a light transmissive substrate is provided with an ablative material deposited on its front side. The substrate is irradiated from its back side at a predetermined energy and fluence level. An excimer laser, or other source of photons of sufficient energy may be used. Energy is absorbed by a portion of the ablative material at an interface between the substrate and the ablative material. This energy is initially confined between the substrate and the rest of the ablative material. It is an advantage of this and other aspects of the present invention over conventional front side laser ablation that the confined energy cannot immediately escape from the system and can be used to promote further ablation. This reduces the total energy required as compared to conventional front side laser ablation. In accordance with another aspect of the present invention, the energy absorbed at the interface causes a rapid state change in the portion of ablative material at the interface. While the exact mechanism of ablation is not certain, it is believed to be a form of ablative photodecomposition brought about by a multiphoton excitation process. It is believed that an excited electron plasma or the like forms at the interface. The confined energy at the interface builds up to an activation threshold sufficient to ablate an overlying adjacent column of ablative material. The adjacent column is fragmented and ejected at a supersonic velocity.

In accordance with another aspect of the present invention, photons impact and excite electrons in the portion of the ablative material at the interface. It is believed that the momentum and energy of the excited electrons detaches an overlying, adjacent column of ablative material from the substrate, breaking any adhesion, bonding or the like. It is also believed that the energy of the excited electrons shear, tear or fragment the atomic structure or electron lattice coupling of the adjacent column of ablative material. Such material is ejected from the substrate at high velocity. Surrounding material remains intact on the substrate, leaving a vacated area with edge resolution defined by the wavelength of light used and atomic structure of the material ejected.

It will be appreciated that this aspect of the present invention is capable of achieving geometries with resolution down to approximately .3 microns with a 308 nm excimer laser. Higher resolution may be obtained with shorter wavelength light sources. It is an advantage of this and other aspects of the present invention that there is no undercutting as with conventional chemical processes, and there is substantially no splatter of the type that occurs with front side laser ablation. In accordance with yet another aspect of the present invention, irradiation may be selectively applied to the back side of the substrate through the use of a mask means, such as a contact mask, projection mask, or the like, for selecting at least one area of the ablative material to be ablated. Irradiation is blocked from areas not selected for ablation. It is an advantage of this aspect of the present invention that the mask means is protected from the ablative material by the substrate and a contact mask adjacent to the back side of the substrate may be used.

Energy is initially absorbed and confined at the interface, in a geometry defined by the mask means. Thus, a precise amount of material can be selected for ablation, as defined by the mask means, the atomic structure of the material, and the wavelength of light used which limits edge definition. It will be appreciated that the dimensional parameters of the ablation can be closely controlled by the geometry of the mask means on the back side of the substrate, the composition of the substrate material, and the wavelength and energy level of the applied radiant energy. In accordance with another aspect of the present invention, back-side photo-induced ablation may be used as part of a process to form color filter elements for a display device or the like. A light transmissive substrate having a front side and a back side is provided. The front side of the substrate may be coated with an adhesion promoter. An adhesion promoter may be necessary for ablative materials that do not readily adhere to the substrate. The front side of said substrate is then coated with a layer of ablative framing material, such as black polyimide or the like, which is cured on the substrate. At least one color material, such as red, green or blue polyimide or the like is provided. For each color material a mask means, such as a contact mask or projection mask, is used to select at least one pixel area upon the substrate for the deposition of the color material; the pixel area is irradiated through the back side of the substrate, ablating the framing material from the pixel area; and the color material is deposited and cured in the vacated pixel area. These steps are repeated separately for each successive color material.

This and other aspects of the present invention allow the formation of color filters with high resolution and with fewer process steps and toxic chemicals than conventional photolithographic methods. This leads to decreased cost, less chemical waste, and higher throughput due to simplified processing. In addition, less total energy is used than in conventional front side laser ablation, and higher resolution and edge definition is obtained with extreme repeatability. BRIEF DESCRIPTION OF THE DRAWINGS

These and other advantages of the present invention may be appreciated from studying the following detailed description of the presently preferred exemplary embodiment together with the drawings in which:

Figures 1A-1C are side sectional views of a first method according to the present invention.

Figure 2A-2G are side sectional views of an alternate method according to the present invention.

Detailed Description of the Presently Preferred Exemplary Embodiment

This invention relates to an improved method of photo-induced ablation. Referring to Figure 1A, a first method according to the present invention provides a light transmissive substrate 100, such as glass, composites, quartz, silicon, plastics or any like material substantially transmissive to light of a given wavelength, having a front side 102 and a back side 104. In the presently preferred exemplary embodiment, a glass wafer approximately 1 mm thick is used as the substrate.

The front side 102 of said substrate is adjacent to, and forms an interface with, a layer of ablative material 106, such as dyed, pigmented, or generic polyimides, pigmented polyacrylate, acrylics, epoxy, dyed gelatin, metals such as indium-tin-oxide, photoresist or like material absorbing radiant energy at a given wavelength. A large variety of ablative materials may be used and are in no way limited to the exemplary materials listed above. What is necessary is that the ablative material be susceptible to a rapid state or structural change, such as ablative photodecomposition, when exposed to radiant energy of a predetermined wavelength, threshold energy and fluence. This depends upon the thickness of the layer of ablative material used, and the optical energy absorption coefficient of the ablative material at that thickness for a given wavelength of light. In addition, the threshold energy level for the ablative material at a given wavelength must be lower than that which will destroy the substrate 100. Table 1 lists several exemplary ablative materials, including dyed and generic polyimides and pigmented aerylate, and their absorption coefficients for 308 nm wavelength light at a given thickness. The dyed and generic polyimides, indicated in Table 1 as PiC and BSI polyimide respectively, were provided by Brewer Science, Inc. and were prepared according to conventional procedures disclosed in U.S. Patent No. 4,876,165. The other materials listed are Fuji-Hunt's pigmented polyacrylate color filter materials and were purchased from color filter materials supplier, OCG

Microelectronics. The thickness of the ablative materials was measured by an Alpha Step Profilometer and their absorption spectra was measured by a Shimadzu UV- 2101 UV-VIS Spectrophotometer. TABLE 1

Ablative Thickness Absorbance Absorption

Material in urn Coefficient in cm^"1

PiC Blue 02 1.4 2.706 1.8xl0⁴

PiC Blue 09 1.4 2.801 2.0X10⁴

PiC Green 02 1.3 2.734 2. lxlO⁴

PiC Green 103 1.5 2.779 1.9X10⁴

PiC Red 02 1.4 2.745 2. OxlO⁴

PiC DARC 100 2.4 1.970 0.82X10⁴

BSI Polyimide 1.1 2.686 2.4X10⁴

Green CG2000 2.2 1.643 0.75X10⁴

Red CR2000 1.8 2.674 1.5X10⁴

Blue CB2000 2.0 2.710 1.4X10⁴

Black CK2000 1.3 2.745 1.4X10⁴

These exemplary materials show strong absorption at the given wavelength of 308 nm, and may generally be ablated with a single 45 nanosecond pulse from a 308 nm excimer laser with an energy and fluence threshold of approximately 300 mJ/cm². These exemplary ablative materials are susceptible to ablative photodecomposition capable of shearing the atomic structure of the material at a resolution of approximately .3 microns, and have the potential for even greater resolution.

The ablative material may be deposited on the substrate using any of several deposition techniques well known to the art, including squeegee deposition, spin coating, printing, electroplating and the like. In the presently preferred exemplary embodiment, a polyimide layer from 1 to 2 microns thick is deposited on the substrate with the use of a squeegee blade.

The substrate may be cleaned with acetone, dried, and optionally coated with a conventional adhesion promoter before being coated with the ablative material. Adhesion promoters may. be necessary for ablative material that does not readily adhere to the substrate, and for most ablative materials use of an adhesion promoter will increase the resulting edge definition. An adhesion promoter has been found necessary to adhere the preferred ablative materials described above in order to obtain high edge definition. Such adhesion promoters are well known in the art. See U.S. Patent No. 4,876,165. It will be readily understood by those skilled in the art that a variety of adhesion promoters and methods for urging adhesion may be used, and will vary depending upon the particular ablative material and substrate used.

Referring to Figure 1A, in accordance with an aspect of the first embodiment according to the present invention, radiant energy 108, at a predetermined wavelength and energy and fluence level, from a light source (not shown) such as an excimer laser is applied to the back side 104 of the substrate 100. The invention is not limited to the use of ultraviolet light. Any source of sufficient radiant energy may be used. Also, any substrate at least partially transmissive to light of a given wavelength may be used. What is necessary is that the light source import sufficient energy in the form of activator photons through the substrate to remove the ablative material. It is recognized that a much larger range of substrates may be used with x-ray lasers and other short wavelength light sources than with visible or even ultraviolet light. At the same time, this may reduce the range of acceptable ablative materials which must absorb sufficient energy at the given wavelength. Also, a less transmissive substrate may be used if a higher energy light source is used. However, for a given wavelength light source, the ablative material must be able to absorb a threshold energy and ablate before the substrate is damaged. In the presently preferred exemplary embodiment, the light source is a 308 nm, 300 hertz pulse excimer laser with a fluence of 300 mJ/cm². Referring to Figure 1A, radiant energy 108 may be selectively applied to the back side 104 of the substrate through the use of a mask means 110, such as a contact mask, projection mask, or the like, for selecting at least one area of the ablative material 106 to be ablated. Such mask means are well known to the art. Irradiation is blocked from areas not selected for ablation. The mask means 110 is protected from the ablative material 106 by the substrate 100. This allows the use of a contact mask adjacent to the back side 104 of the substrate, which simplifies mask alignment.

Referring to Figure IB, energy is absorbed by a portion of the ablative material 112 at the interface between the substrate and the ablative material. This energy is initially confined between the substrate 100 and the rest of the ablative material 106 in a geometry defined by the mask means 110. The confined energy cannot immediately escape from the system and can be used to promote further ablation. The energy absorbed at the interface causes a rapid state change in the portion of ablative material 112 at the interface. While the exact mechanism of ablation is not certain, it is believed to be a form of ablative photodecomposition brought about by a multiphoton excitation process. It is believed that an excited electron plasma or the like forms in the portion of ablative material 112 at the interface. The confined energy at the interface builds up to an activation threshold sufficient to ablate an overlying adjacent column 114 of ablative material. As discussed above, a column of generic polyimide 1 to 2 microns thick may be ablated with approximately a single 45 nanosecond pulse of 308 nm wavelength light at 300 mJ/cm². Referring to

Figures IB and 1C, the adjacent column 114 is fragmented, and may be partially or completely vaporized. The fragmented column is ejected at a supersonic velocity, leaving a vacated ablated area on the substrate. Photons impact and excite electrons in the portion of the ablative material 112 at the interface. It is believed that the momentum and energy of the excited electrons detaches the overlying, adjacent column 114 of ablative material from the substrate, breaking any adhesion, bonding or the like. It is also believed that the momentum and energy of the excited electrons shear, tear or fragment the atomic structure or electron lattice coupling of the column 114 of ablative material. Such material is ejected from the substrate at high velocity. Surrounding material remains intact on the substrate, leaving a vacated area with edge resolution defined by the wavelength of light used and atomic structure of the material ejected. As described previously, an adhesion promoter may be necessary for sufficient adhesion of the ablative material to the substrate. This helps keep the surrounding material intact on the substrate, and provides for improved edge definition.

It will be appreciated that this aspect of the present invention, is capable of achieving geometries with resolution down to approximately .3 microns with a 308 nm excimer laser and is capable of producing higher resolution with shorter wavelength light sources. Thus, a precise amount of material can be selected for ablation, as defined by the mask means 110, the atomic structure of the ablative material, and the wavelength of light used which limits edge definition. It will be appreciated that the dimensional parameters of the ablation can be closely controlled by the geometry of the mask means 110 on the back side of the substrate, the composition of the substrate material, and the energy level and wavelength of the applied radiant energy 108. Less energy is required for the method according to the present invention than for the conventional front side laser ablation method. For instance, a 308 nm, 300 hertz pulse excimer laser with a fluence of 300 mJ/cm² may be used in both methods. In the method according to the present invention, a single pulse of approximately 45 nanoseconds will ablate a layer of generic polyimide about 1 to 2 microns thick. Approximately 10 pulses are required to ablate the same layer, at reduced resolution, for conventional front side laser ablation. Even if a 500 mJ/cm² laser is used, about 5 pulses are needed. The reduced energy requirement results directly from the confinement of energy at the interface between the ablative material—generic polyimide in this example—and the substrate—glass in this example. This energy is recycled in the system and used for further ablation. In conventional front side laser ablation, this energy would escape off the top surface as the polyimide is vaporized from the top down.

Referring to Figure 2, a second method according to the present invention uses back-side photo-induced ablation as part of a process to form color filter elements for a color display device or the like. Referring to Figure 2A, a light transmissive substrate 100 having a front side 102 and a back side 104 is provided. The front side 102 of the substrate may be coated with an adhesion promoter as described previously. The front side of said substrate is then coated with a layer of ablative framing material 200, such as black polyimide or the like, which is cured on the substrate by baking, radiation, chemical curing, or similar means. The previous discussion of ablative materials applies to the ablative framing material used in this process. At least one color material, such as colored polyimide or the like is provided. In the presently preferred exemplary embodiment, red 202, blue 204, and green 206 polyimide are used. Of course, it is understood that a variety of colors and materials could be used in almost unlimited combinations.

Referring to Figure 2B, for each color material a mask means 208, such as a contact mask or projection mask, is used to select at least one pixel area 210 upon the substrate for the deposition of the color material; the pixel area 210 is irradiated with radiant energy 212 through the back side of the substrate at a predetermined wavelength and energy and fluence level, ablating the framing material 200 from the pixel area 210; and, referring to Figure 2C, the color material, here red polyimide 202, is deposited and cured in the vacated pixel area 210. Referring to Figures 2D-2G, these steps are repeated separately for each successive color material—here blue polyimide 204 and green polyimide 206.

The ablation of the pixel area 210 occurs through the mechanisms described previously. In the presently preferred exemplary embodiment approximately a single 45 nanosecond pulse of 308 nm wavelength light at 300 mJ/cm² is used to ablate the framing material. Energy is absorbed at an interface between the framing material 200 and the substrate 100. This energy is initially confined between the substrate 100 and the rest of the framing material 200 in a geometry defined by the mask means 208. The confined energy cannot immediately escape from the system and can be used to promote further ablation. The energy absorbed at the interface causes a rapid state change in the portion of framing material at the interface. While the exact mechanism of ablation is not certain, it is believed to be a form of ablative photodecomposition brought about by a multiphoton excitation process. It is believed that an excited electron plasma or the like forms in the portion of framing material at the interface. The confined energy at the interface builds up to an activation threshold sufficient to ablate overlying framing material in the pixel area 210.

The mechanisms for the other steps used in the process—coating, using mask means to select pixel areas, and curing—are well known to the art. Many different methods of coating, selecting pixel areas, and curing may be used interchangeably without removing the process from the scope of the present invention. In fact, curing of some materials may occur just by drying or the passage of time, yet should still be considered within the scope of the present invention. In any of various possible configurations, the present invention allows the formation of color filters with high resolution and with fewer process steps and toxic chemicals than conventional photolithographic methods. In addition, as discussed previously, less total energy is used than in conventional front side laser ablation.

The foregoing and other aspects of the present invention are also able to provide much greater edge definition than conventional methods. There is no undercut as with conventional chemical processes, and there is no splatter as with conventional front side laser ablation.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The present invention is intended to cover all of the various configurations in which radiant energy can be confined at the interface between a substrate and an adjacent layer of ablative material, and recycled for further ablation. For instance, different light sources allow different substrates and ablative materials to be used. In particular, an x-ray laser may allow silicon substrates to be used with an ablative material capable of absorbing sufficient energy at that wavelength. This may allow design of high resolution semiconductor electronics without many of the constraints of current processes. Also light transmissive substrates need not be completely transmissive to all light, and can in fact completely block visible light. The substrate must simply allow photons of a given wavelength to impart sufficient energy to the ablative material.

While a variety of embodiments have been disclosed, it will be readily apparent to those skilled in the art that numerous other modifications and variations not mentioned above can still be made without departing from the spirit and scope of the invention claimed below.

Claims

WHAT IS CLAIMED IS;

1. A method for back-side photo-induced ablation comprising the steps of: providing a light transmissive substrate having a front side and a back side; the front side of said substrate being adjacent to a layer of ablative material forming an interface between the ablative material and the front side of the substrate; irradiating the back side of said substrate at a predetermined energy and fluence level such that sufficient energy is absorbed by a portion of the ablative material at the interface between the front side of said substrate and the adjacent layer of ablative material to remove an amount of said ablative material from the substrate; using said absorbed energy to remove the amount of said ablative material from the substrate.

2. The method of claim 1, wherein the removal of said amount of ablative material is achieved by substantial vaporization of the amount of ablative material.

3. The method of claim 1, wherein the removal of said amount of ablative material is achieved by fragmentation and ejectment of the ablative material at supersonic velocities.

4. A method for back-side photo-induced ablation comprising the steps of: providing a light transmissive substrate having a front side and a back side; the front side of said substrate being adjacent to a layer of ablative material forming an interface between the ablative material and the front side of the substrate; irradiating the back side of said substrate at a predetermined energy and fluence level sufficient to cause a rapid state change in a portion of the ablative material at the interface between the front side of said substrate and the adjacent layer of ablative material; using energy of said state change to remove an amount of said ablative material from the substrate.

5. The method of claim 4, wherein irradiation is provided by a light source at a given wavelength, wherein the substrate is substantially transmissive to light of the given wavelength, and wherein the ablative material absorbs sufficient energy at the given wavelength to cause the rapid state change.

6. The method of claim 4, wherein the ablative material is selected from the group consisting of acrylic, gelatin, and polyimide.

7. The method of claim 4, wherein irradiation is provided by a laser.

8. The method of claim 4, wherein irradiation is provided by an excimer laser.

9. The method of claim 4, wherein the substrate is selected from the group consisting of glass, plastic, and quartz.

10. The method of claim 4, wherein irradiation is provided by an x-ray laser, and the substrate is silicon.

11. The method of claim 4, wherein the ablative material is adhered to the substrate with the aid of an adhesion promoter.

12. The method of claim 4, wherein the removal of said amount of ablative material is achieved by substantial vaporization of the amount of ablative material.

13. The method of claim 4, wherein the removal of said amount of ablative material is achieved by fragmentation and ejectment of the ablative material at supersonic velocities.

14. The method of claim 5, wherein the light source is an excimer laser, the ablative material is selected from the group consisting of acrylic, gelatin and polyimide, and the substrate is selected from the group consisting of glass, plastic and quartz.

15. A method for back-side photo-induced ablation comprising the steps of: providing a light transmissive substrate having a front side and a back side; the front side of said substrate being adjacent to a layer of ablative material forming an interface between the ablative material and the front side of the substrate; irradiating the back side of said substrate at a predetermined energy and fluence level sufficient to cause ablative photodecomposition in a portion of the ablative material at the interface between the front side of said substrate and the adjacent layer of ablative material; using energy of said ablative photodecomposition to remove an amount of said ablative material from the substrate.

16. The method of claim 15, wherein the removal of said amount of ablative material is achieved by substantial vaporization of the amount of ablative material.

17. The method of claim 15, wherein the removal of said amount of ablative material is achieved by fragmentation and ejectment of the ablative material at supersonic velocities.

18. The method of claim 4 further comprising the steps of: providing a mask means for selecting at least one area of the ablative material to be ablated; and using the mask means to select the at least one area of the ablative material to be ablated and to block other areas of the ablative material from irradiation; and wherein the amount of the ablative material removed from the substrate is a desired amount as defined by the mask means, wavelength of the irradiation, and atomic structure of the ablative material.

19. The method of claim 18, wherein the mask means is placed substantially adjacent to the back side of said substrate.

20. The method of claim 19, wherein the mask means is a contact mask.

21. The method of claim 15 further comprising the steps of: providing a mask means for selecting at least one area of the ablative material to be ablated; and using the mask means to select the at least one area of the ablative material to be ablated and to block other areas of the ablative material from irradiation; and wherein the amount of the ablative material removed from the substrate is a desired amount as defined by the mask means, wavelength of the irradiation and atomic structure of the ablative material.

22. The method of claim 21, wherein the mask means is placed substantially adjacent to the back side of said substrate.

23. The method of claim 22, wherein the mask means is a contact mask.

24. A method for back-side photo-induced ablation comprising the steps of: providing a light transmissive substrate having a front side and a back side; coating the front side of said substrate with a layer of ablative material, forming an interface between the ablative material and the front side of the substrate; curing the ablative material on the substrate; irradiating the back side of said substrate at a predetermined wavelength and energy and fluence level sufficient to cause a rapid state change in a portion of the ablative material at the interface between the front side of said substrate and the layer of ablative material; using energy of said state change to remove an amount of said ablative material from the substrate.

25. The method of claim 24, further comprising the step of coating the front side of said substrate with an adhesion promoter before coating the front side of the substrate with the layer of ablative material.

26. A method for back-side photo-induced ablation comprising the steps of: providing a light transmissive substrate having a front side and a back side; providing an adjacent layer of ablative material substantially adhered to the front side of said substrate, forming an interface between the ablative material and the front side of the substrate; providing a mask means for selecting at least one area of the ablative material to be ablated; irradiating the back side of said substrate through the mask means with photons of radiant energy at a predetermined wavelength and energy and fluence level sufficient to cause a rapid state change in a portion of the ablative material at the interface between the front side of said substrate and an adjacent column of ablative material; causing said photons to impact and excite electrons in the portion of the ablative material at the interface; using momentum and energy of said excited electrons to break the substantial adhesion between the ablative material and the substrate at the interface; using the momentum and the energy of said excited electrons to shear an atomic structure of the column of ablative material from adjacent ablative material still substantially adhered to the substrate; using the momentum and the energy of said excited electrons to eject the column of ablative material from the substrate, leaving a vacated area with an edge definition defined by the wavelength of the photons and atomic structure of the ablative material.

27. A process for forming a color filter element, comprising the steps of: providing a light transmissive substrate having a front side and a back side; coating the front side of said substrate with a layer of ablative framing material, forming an interface between the framing material and the front side of the substrate; curing the framing material on the substrate; providing at least one color material; for each color material: (a) providing a mask means for selecting at least one pixel area upon the substrate; (b) irradiating the back side of said substrate through the mask means with photons of radiant energy at a predetermined wavelength and energy and fluence level sufficient to cause a rapid state change in a portion of the framing material in the pixel area at an interface between the front side of said substrate and the adjacent layer of framing material; (c) using energy of said state change to remove the framing material from the pixel area; (d) depositing the color material in the pixel area; (e) curing the color material on the substrate.

28. The method of claim 27, further comprising the step of coating the front side of said substrate with an adhesion promoter before coating the front side of the substrate with the filter material.

29. The process of claim 27, wherein the filter material is substantially adhered to the substrate; and wherein the step of using said energy of said state change to remove the framing material from the pixel area further comprises: causing said photons to impact and excite electrons in the portion of the framing material at the interface; using momentum and energy of said excited electrons to break the substantial adhesion between the framing material in the pixel area and the substrate at the interface; using the momentum and the energy of said excited electrons to shear an atomic structure of the framing material in the pixel area from adjacent framing material still substantially adhered to the substrate; using the momentum and energy of said excited electrons to eject the framing material from the pixel area leaving a vacated pixel area with an edge definition defined by the wavelength of the photons and atomic structure of the framing material.

30. The process of claim 27, wherein the framing and color materials are selected from the group consisting of acrylic, gelatin and polyimide.

31. The process of claim 27, wherein the framing material is black; and wherein there are three color materials: a red color material, a blue color material, and a green color material.

32. The process of claim 30, wherein the photons are provided by an excimer laser, and the substrate is selected from the group consisting of glass, plastic and quartz.

33. A method for back-side photo-induced ablation comprising the steps of: providing a light transmissive substrate having a front side and a back side; the front side of said substrate being adjacent to a layer of ablative material; using a laser to irradiate the back side of said substrate at a predetermined energy and fluence level sufficient to ablate a portion of the ablative material from the front side of the substrate; whereby the portion of the ablative material is ablated from the substrate.

34. A process for forming a color filter element, comprising the steps of: providing a light transmissive substrate having a front side and a back side; coating the front side of said substrate with a layer of ablative framing material; curing the framing material on the substrate; providing at least one color material; providing a mask means for selecting at least one pixel area upon the substrate; using a laser to irradiate the back side of said substrate through the mask means at a predetermined energy and fluence level sufficient to ablate the framing material from the at least one pixel area, thereby leaving a vacated pixel area; depositing the color material in the vacated pixel area ; curing the color material on the substrate .