Plastic and nonmetallic article shaping or treating: processes – With printing or coating of workpiece
Utility Patent
1998-02-23
2001-01-02
Ball, Michael W. (Department: 1733)
Plastic and nonmetallic article shaping or treating: processes
With printing or coating of workpiece
C264S250000, C264S299000, C445S024000
Utility Patent
active
06168737
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for forming and patterning porous dielectrics, particularly for use as electrode spacers in microelectronics applications.
2. Description of Related Art
Dielectric materials are needed as electrode spacers in microelectronics circuits and devices, such as field emission displays. Flat panel displays, in particular, incorporate spacers in the evacuated cavity between a display faceplate and the emitting baseplate. The emitting surface has at least one electron emitter for each pixel on the display surface, and a high voltage differential is maintained between the two electrodes. The spacer must be non-conductive and not interfere with the flow of electrons between the plates. The spacer material must be stable under electron bombardment. The interelectrode spacing must be small and uniform to provide high image resolution. To manufacture lightweight, durable, portable large-area screens, the spacer material must be lightweight, yet have the mechanical strength capable of withstanding atmospheric pressure and other external pressures placed on the display screen. Microelectronic devices also normally require that the dielectric spacers have very small features and high aspect ratios (i.e., height to thickness ratios) so as not to interfere with display resolution.
Various methods have been developed to manufacture interelectrode spacers. U.S. Pat. No. 5,205,770, entitled “Method to form high aspect ratio supports (spacers) for field emission displays using micro-saw technology”, discloses a technique that forms a mold using micro-saw technology and removes the mold by selective (chemical) etching. U.S. Pat. No. 5,698,932 entitled “Interelectrode spacers for display devices including field emission displays”, discloses the fabrication of aerogel or xerogel spacers as a separate element in the display device using photochemical patterning and etching techniques. Both of these techniques employ chemical etching, which is time-consuming and expensive.
U.S. Pat. No. 5,658,832 to Bernhardt, entitled “Method of forming a spacer for field emission flat panel displays” discloses a method for making aerogel spacers, developed at Lawrence Livermore National Laboratory, that does not require chemical etching. The spacer is fabricated using a template or mold having through-holes formed therein; this template is placed in contact with the substrate. A release agent is applied to the mold before an aerogel precursor solution is poured into the holes. After the solution is gelled and dried, the mold is removed from the substrate to expose aerogel spacer structures. The mold and substrate must be in perfect contact to avoid leakage of the solution into the space between the mold and substrate, otherwise thin films of the aerogel form on the substrate.
The researchers at Lawrence Livermore National Laboratory have significantly improved and expanded the process of making spacers and other kinds of dielectric structures using molds. The present method does not require the use of a release agent or the use of a mold during the drying process, and further improves the quality and physical properties of the porous dielectric structures produced.
SUMMARY OF THE INVENTION
The present invention is a process for forming patterned dielectric structures using molds. The method uses sol-gel chemistry to form a porous dielectric material and molding procedures to produce a high aspect ratio pattern. The resulting structures are formed directly on a substrate (such as a glass plate) and comprise inorganic microporous or mesoporous materials, including aerogels and xerogels. Porous materials (i.e., less than full density) are particularly desirable because of their low weight. A variety of structures may be formed, such as posts, cylindrical pillars, and walls. A typical pattern is an array of square posts (e.g., 25 microns on a side), spaced apart by 300 microns and having a height of at least 250 microns. The desired aspect ratios are typically 10 or greater.
The objective of this invention is to fabricate patterned, gel-derived dielectric structures suitable for use in vacuum environments for electronic devices, such as spacers between the faceplate and baseplate of a display panel. Another objective is to provide a low cost method of forming, in a single process step, lightweight dielectric spacers directly on a substrate, such as a faceplate or baseplate of a field emission display.
Other applications of the patterned dielectric structures include insulators in multichip module electronic circuits, microchannel plates for electron gain devices, thermal insulators, and lightweight support structures for space applications. The microporous and mesoporous materials have extremely small pores, which are ideal for high voltage insulators where secondary electron emission must be minimized. In addition, these materials do not contain organics that can outgas and contaminate a vacuum environment.
REFERENCES:
patent: 4266978 (1981-05-01), Prochazka
patent: 4686195 (1987-08-01), Yamane
patent: 4790893 (1988-12-01), Watkins
patent: 4892544 (1990-01-01), Frisch
patent: 5205770 (1993-04-01), Lowrey et al.
patent: 5232549 (1993-08-01), Cathey et al.
patent: 5256360 (1993-10-01), Li
patent: 5484314 (1996-01-01), Farnworth
patent: 5486126 (1996-01-01), Cathey et al.
patent: 5492234 (1996-02-01), Fox
patent: 5503582 (1996-04-01), Cathey et al.
patent: 5509840 (1996-04-01), Huang et al.
patent: 5547483 (1996-08-01), Garcia et al.
patent: 5561343 (1996-10-01), Lowe
patent: 5562517 (1996-10-01), Taylor et al.
patent: 5589731 (1996-12-01), Fahlen et al.
patent: 5629583 (1997-05-01), Jones et al.
patent: 5650690 (1997-07-01), Haven
patent: 5658832 (1997-08-01), Bernhardt et al.
patent: 5663608 (1997-09-01), Jones et al.
patent: 5667418 (1997-09-01), Fahlen et al.
patent: 5675212 (1997-10-01), Schmid et al.
patent: 5698932 (1997-12-01), Cathey et al.
patent: 5700391 (1997-12-01), Nogami et al.
patent: 5746635 (1998-05-01), Spindt et al.
patent: 5750459 (1998-05-01), Marella et al.
patent: 5811031 (1998-09-01), Jansen et al.
patent: 5818168 (1998-10-01), Ushifusa et al.
patent: 5824250 (1998-10-01), Whalen et al.
Hrubesh Lawrence W.
Poco John F.
Ball Michael W.
Musser Barbara J.
The Regents of the University of California
Thompson Alan H.
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