Abstract:
Titanium aluminum nitrogen (“Ti—Al—N”) is deposited onto a semiconductor substrate area to serve as an antireflective coating. For wiring line fabrication processes, the Ti—Al—N layer serves as a cap layer which prevents unwanted reflection of photolithography light (i.e., photons) during fabrication. For field emission display devices (FEDs), the Ti—Al—N layer prevents light originating at the display screen anode from penetrating transistor junctions that would hinder device operation. For the wiring line embodiment, an aluminum conductive layer and a titanium-aluminum underlayer are formed beneath the antireflective cap layer. The Ti—Al underlayer reduces the shrinkage which occurs in the aluminum conductive layer during heat treatment.
Abstract:
A process is provided for forming sharp asperities, useful as field emitters. The process comprises: patterning and doping a silicon substrate. The doped silicon substrate is anodized. The anodized area is then used for field emission tips. The process of the present invention is also useful for low temperature sharpening of tips fabricated by other methods. The tips are anodized, and then exposed to radiant energy, and the resulting oxide is removed.
Abstract:
A method for fabricating sharp asperities. A substrate is provided which has a mask layer disposed thereon, and a layer of micro-spheres is disposed superjacent the mask layer. The micro-spheres are for patterning the mask layer. Portions of the mask layer are selectively removed, thereby forming circular masks. The substrate is isotropically etched, thereby creating sharp asperities.
Abstract:
Electron emitters and a method of fabricating emitters which have a concentration gradient of impurities, such that the highest concentration of impurities is at the apex of the emitters, and decreases toward the base of the emitters. The method comprises the steps of doping, patterning, etching, and oxidizing the substrate, thereby forming the emitters having impurity gradients.
Abstract:
A support structure is provided that enables the use of high-voltage phosphors in field-emission flat panel displays, to maintain the vacuum gap between the cathode and the anode at a constant distance and to prevent distortion of the transparent view screen and backing plate of the display. A number of independent techniques each contributes to the solution of the problem of secondary electron emission. One technique is to alter the geometry of the triple junction of the support structure, the cathode, and the vacuum gap, thereby reducing the electrostatic field created at the triple junction. Reducing the electrostatic field reduces the initial primary electron bombardment originating at the triple junction. Altering the geometry of the support surface with respect to the field lines present at the triple junction also increases the probability that impinging electrons will impact at or nearly at right angles, and will also tend to be directed by the field lines back into the "pocket" created by the shaping of the support structure edge, preventing secondary electrons from escaping and traveling along the structure surface to the anode. In accordance with another technique, the support structure is fluted so as to reduce the average coefficient of secondary electron emission, to trap a proportion of secondary electrons, and to limit the number of hops of other secondary electrons. In another technique, a high resistivity conductive layer is formed at the triple junction in order to reduce the field potential at the triple junction. A similar conductive layer may be formed at the opposite junction of the support structure, the anode, and the vacuum gap. A high resistivity conductive material coated on the surface of the insulating spacer can be used to decrease the charge relaxation time of the insulator, thereby maintaining a constant field potential over the surface of the insulator, reducing areas of high field potential which will tend to accelerate secondary electron emissions. In accordance with other techniques, the support structure is made of a non-porous material and may be coated with a coating having low secondary emission characteristics.
Abstract:
Gated electron emitters are fabricated by processes in which charged particles are passed through a track layer (24, 48, or 144) to form charged-particle tracks (26.sub.1, 50.sub.1, or 146.sub.1). The track layer is etched along the tracks to create open spaces (28.sub.1, 52.sub.1, or 148.sub.1). Electron-emissive elements (30 or 142D) can then be formed at locations respectively centered on the open spaces after which a patterned gate layer (34B, 40B, or 158C) is provided. Alternatively, the open spaces in the track layer can be employed to etch corresponding apertures (54.sub.1) through an underlying non-insulating layer (46) which typically serves as the gate layer. An etch is performed through the apertures to form dielectric open spaces (56.sub.1, 96.sub.1, or 114.sub.1) in an insulating layer (24) that lies below the non-insulating layer. Electron-emissive elements (30B, 30/88D.sub.1, 98/102.sub.1, or 118.sub.1) can subsequently be provided, typically in the dielectric open spaces.
Abstract:
A cold cathode electron source element having a cold cathode on a substrate. The cold cathode has dispersed in a cold cathode base particles of a conductive material having a lower work function than the base and a particle size which is sufficiently smaller than the thickness of the cold cathode. The element can be driven with a low voltage to induce high emission current in a stable manner. The cold cathode is easily processable. The element can have an increased surface area.
Abstract:
A pixel emission current limiting resistance is realized by forming a stack of alternately doped amorphous or polycrystalline silicon layers over the cathodic conductors of a FED driving matrix. The stack of amorphous or polycrystalline silicon layers doped alternately n and p provides at least a reversely biased n/p junction having a leakage current that matches the required level of pixel emission current. The reversely biased junction constitutes a nonlinear series resistance that is quite effective in limiting the emission current through any one of the microtips that form an individually excitable pixel and which are formed on the uppermost layer of the stack.