Patent ID: 6083069
Filing Date: 2000-07-04
Classification: G11C,H01J,H01L

Abstract:
A process for manufacturing a micro vacuum tube, comprising the steps of:patterning and etching a first conductive layer to form a first disk, having a first diameter;onto said first disk, successively depositing a first layer of a dielectric, a second conductive layer, a second layer of a dielectric, and a layer of silicon nitride having a top surface;patterning and etching the layers on said first disk to form a pedestal having a second diameter that is less than said first diameter;in the silicon nitride, forming a circular hole having a vertical wall that extends as far as said second dielectric layer;on said vertical wall, forming a silicon nitride spacer having a thickness value that varies from maximum furthest from said top surface to zero at said top surface;using the spacer as a mask, etching the second dielectric, the second conductive layer, and the first dielectric down as far as said first conductive layer;depositing a sacrificial layer onto said top surface and into said hole, thereby forming a concave cusp having a central depression and an outer rim;patterning and etching said sacrificial layer to form a pole hole, extending to said top surface and located between said central depression and said outer rim;depositing a third conductive layer over the sacrificial layer to a thickness sufficient to overfill the pole hole and the central depression;patterning and etching said third conductive layer to form a second disk that includes the pole hole and having a diameter that is less than said second diameter;selectively removing the sacrificial layer thereby forming a microtip having a top surface and comprising a conductive convex cusp centrally located above the circular hole and supported by a conductive pole; andin a vacuum environment, depositing a metal layer that extends from the top surface of the silicon nitride to the top surface of the microtip.