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FEA with suspended focusing electrode Disclosure Number: IPCOM000005377D
Publication Date: 2001-Sep-18
Document File: 5 page(s) / 347K

Publishing Venue

The Prior Art Database

Related People

John Lannon: INVENTOR


The basic idea is to improve the focus of the electron beams emitted from tips in a gated FEA by mounting a suspended "focusing" electrode on the FEA chip using MCNC's flip chip technology. The gated FEA chip could be fabricated using standard FEA processing schemes with one additional feature. Solder bump pads would be deposited around the perimeter of the array on the chip (see Fig. 2a). A second die (ceramic or some other rigid material) would be patterned, etched (formation of through holes), patterned again, metallized (on both sides), and solder bumped to "mate" with the FEA chip (see Fig. 2a). The solder bumps would be electrically isolated from the field metal of the focusing electrode. Then, the focusing electrode would be "flipped" on to the FEA chip using techniques developed previously at MCNC. Figure 2b illustrates a side view of the resulting structure. The distance of the focusing electrode from the gate electrode is dependent upon the size of the solder bumps used to bond the two chips together. In theory, a substantial gap between the focusing and gate electrodes should lead to improved focusing of the field emitted electron beams.

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Full Name(s) of Inventor




John M. Lannon Jr.




Dorota Temple



W. Dev Palmer



Title of Invention (short and Descriptive)

FEA with suspended focusing electrode

Time Stamp

Problem Solved By This Invention (Summary)

Allows Field Emitter Arrays (FEAs) to be used in applications where electron beam resolutions on the nm scale are required (e.g., e-beam lithography)

Manager or Director Approval

1. Date the invention was conceived: 7/13/01

2. Has the invention been reduced to practice? YES NO

If yes, when?

3. Has the invention been published or is it about to be published? YES NO

If yes, when?

4. In what context was the invention made?

Project B&P

5. Please indicate any knowledge you may have of any related work outside of MCNC:

To my knowledge, this particular structure has not been investigated. The area of focusing field emitted electrons has been researched for many years and other approaches for focusing the electrons have been developed.

6. Is the invention a new process, composition of matter, a device or one or more products?

This device structure should provide a new way of focusing electrons emitted from FEAs to obtain nm scale electron beam resolution; the novelty is in the way the FEAs are integrated with a focusing electrode (electronic lens).

7. A new use for, or an improvement to, an existing process? YES NO

8. Write a brief descriptive abstract of your invention without making any disclosure. This will be used for marketing purposes.

The basic idea is to integrate a second electrode (focusing electrode) a few microns above a gated Field Emitter Array (FEA). The resulting device structure should greatly improve the focus of the electron beams emitted from individual tips in the FEA.

9. From the description, pick out and expand on novel and unusual features. How does the invention differ from present technology? What problems does it solve or what advantage(s) does it possess?

The novelty of this invention lies in the use of flip chip technology (solder bumping) to suspend a focusing electrode above a FEA. The increased vertical distance between the gate on the FEA and the focusing electrode should greatly improve the focus of the electron beams from individual field emitter tips. Two competing approaches are in-plane focusing electrodes that severely limit the density of tips in an array and multi-layer electrodes that are limited in the thickness of dielectrics that can be deposited on the gate metal (see Fig. 1a and 1b, respectively).

10. If not indicated previously, what are possible uses for the invention? In addition to immediate applications, are there other uses that might be realized in the f...