Abstract: A semiconductor device having a short gate length is fabricated. The short gate length is obtained by utilizing the fact that an unannealed silicon nitride can be isotropically etched while not etching an annealed silicon nitride layer. The method comprises forming a first silicon nitride 13 on a semiconductor material 10, annealing layer 13, forming an insulating layer 15, a second silicon nitride layer 17 and a masking layer 19, undercutting a portion of layers 17 and 15, removing the masking layer, annealing the second silicon nitride 17, implanting to form channel region 20 having portions 21 and 22, undercutting a portion of the insulating layer 15, removing the second silicon nitride 17 and the first silicon nitride 13 not covered by layer 15, forming gate 23 having effective gate length 30 and source/drain 25/26.

Abstract: A universal duct elbow as for the vent system of a clothes dryer, formed of a body and a pair of swivel sleeves rotational on the body. The body has an outer 180.degree. portion of a configuration like that of a quarter toroid, and an inner 180.degree. portion like a square type elbow. The center line radius is less than about 0.6 of the duct diameter, enabling a duct assembly using the elbow to fit into a space only slightly larger than the duct diameter. The body is formed of an L-shaped plate having flow openings in the two legs of the L, plus two joined mirror image, arcuate elements. At these sleeves are radially extending flanges of the legs of the L to enable attachment to a wall.

Abstract: A dryer duct assembly employs two universal elbow components and at least one flexible component. The flexible component has ends capable of connecting to another flexible component or to a universal component without the use of other devices such as hose clamps to secure connection. Each elbow has ends capable of attaching either to the wall opening or the dryer, in addition to attaching to the flexible component in the same manner as the flexible components may attach to each other. The elbow has an outer portion resembling the outer portion of a quarter-toroid, and a square type inner portion. The outer portion is made of a pair of mirror image hemi portions connected at adjacent flanges. The inner portion has an L-shaped plate with flow-through orifices in each leg of the L.

Abstract: A flexible duct assembly having a thin peripheral wall formed with helical, i.e., sprial, ribs and adjacent grooves or valleys, the apex of each rib and valley advancing helically with axial extension of the duct, and a rotary joint on at least one end of the duct to relieve the torque otherwise resulting from the helical advancement.

Abstract: Disclosed is a metal dryer exhaust duct assembly using a pair of flexible corrugated metal ducts capable of linear extension and capable of reorientation of the duct ends, a pair of elbow connectors, one for attachment to a dryer exhaust outlet and the other for attachment to a wall inlet. Each duct has a swivel connection to its respective elbow connector, using a sleeve which interfits with the elbow connector by a peripheral projection and recess arrangement. Each duct can also be interfit with another such duct. The two ducts can be attached respectively to an dryer and a wall spaced from each other, and are vertically self supporting, whereby when the dryer is moved adjacent the wall, a person can readily telescopically interconnect the ends of the ducts over the top of the dryer. One or more pieces of the duct may be used to span the distance between the dryer and the wall outlet.

Abstract: A carton containing a compressed flexible duct for selected removal of portions of the duct, the carton having a first pair of end flaps and a second pair of end flaps for closing the top end of the carton. The flaps of the first pair each have a length more than one-half the length of the top end to fold segmentally into diagonal extensions into the carton where the distal edges of the first pair can abut each other. The second pair of flaps each has a pair of diagonal creases from the end edges to the distal edge to allow folding of the flap ends to form stops for the first pair of flaps to retain the compressed duct in the carton.

Abstract: A flexible duct and carton for retaining and enabling controlled dispensing of the flexible duct positioned therein, the duct preferably being in a U-shaped orientation abutting end walls of the carton. The carton has a width about the diameter of the duct, and a breadth at least about twice the diameter of the duct. A breakout panel in a side wall adjacent one of the end walls forms a lateral outlet opening which has a width and a height greater than the duct diameter, whereby an end of the duct can be turned 90.degree. and pulled out in controlled lengths.

Abstract: The specification discloses a low-cost, simple, and efficient duct system for conveying heated and/or cooled air throughout a building. The system includes duct assemblies and transition components for interconnecting the duct assemblies. Each duct assembly includes an insulated duct having a rigid sleeve within at least one end. Each sleeve includes an abutment ring and orifices in the ring for permitting air to flow into the insulated layer to balloon the layer and improve its insulative effect. Each transition component includes a rigid external skeleton and a plurality of duct board panels fitted therein. After the sleeves are fitted within openings in the duct board panels, the tabs are deformed to retain the abutment rings in engagement with the panels.

Abstract: The specification discloses a low-cost, simple, and efficient duct system for conveying heated and/or cooled air throughout a building. The system includes duct assemblies and transition components for interconnecting the duct assemblies. Each duct assembly includes an insulated duct having a rigid sleeve within at least one end. Each sleeve includes an abutment ring and orifices in the ring for permitting air to flow into the insulated layer to balloon the layer and improve its insulative effect. Each transition component includes a rigid external skeleton and a plurality of duct board panels fitted therein. After the sleeves are fitted within openings in the duct board panels, the tabs are deformed to retain the abutment rings in engagement with the panels.