Abstract:
A method of fabricating micro-electromechanical switches (MEMS) integrated with conventional semiconductor interconnect levels, using compatible processes and materials is described. The method is based upon fabricating a capacitive switch that is easily modified to produce various configurations for contact switching and any number of metal-dielectric-metal switches. The process starts with a copper damascene interconnect layer, made of metal conductors inlaid in a dielectric. All or portions of the copper interconnects are recessed to a degree sufficient to provide a capacitive air gap when the switch is in the closed state, as well as provide space for a protective layer of, e.g., Ta/TaN. The metal structures defined within the area specified for the switch act as actuator electrodes to pull down the movable beam and provide one or more paths for the switched signal to traverse. The advantage of an air gap is that air is not subject to charge storage or trapping that can cause reliability and voltage drift problems. Instead of recessing the electrodes to provide a gap, one may just add dielectric on or around the electrode. The next layer is another dielectric layer which is deposited to the desired thickness of the gap formed between the lower electrodes and the moveable beam that forms the switching device. Vias are fabricated through this dielectric to provide connections between the metal interconnect layer and the next metal layer which will also contain the switchable beam. The via layer is then patterned and etched to provide a cavity area which contains the lower activation electrodes as well as the signal paths. The cavity is then back-filled with a sacrificial release material. This release material is then planarized with the top of the dielectric, thereby providing a planar surface upon which the beam layer is constructed.
Abstract:
A process is described for forming a common input-output (I/O) site that is suitable for both wire-bond and solder bump flip chip connections, such as controlled-collapse chip connections (C4). The present invention is particularly suited to semiconductor chips that use copper as the interconnection material, in which the soft dielectrics used in manufacturing such chips are susceptible to damage due to bonding forces. The present invention reduces the risk of damage by providing site having a noble metal on the top surface of the pad, while providing a diffusion barrier to maintain the high conductivity of the metal interconnects. Process steps for forming an I/O site within a substrate are reduced by providing a method for selectively depositing metal layers in a feature formed in the substrate. Since the I/O sites of the present invention may be used for either wire-bond or solder bump connections, this provides increased flexibility for chip interconnection options, while also reducing process costs.
Abstract:
A three-dimensional micro-electromechanical (MEM) varactor is described wherein a movable beam (50) and fixed electrodes (51) are respectively fabricated on separate substrates coupled to each other. The movable beam with comb-drive electrodes are fabricated on the "chip side" while the fixed bottom electrode is fabricated on a separated substrate "carrier side". Upon fabrication of the device on both surfaces of the substrate, the chip side device is diced and "flipped over", aligned and joined to the "carrier" substrate to form the final device. Comb-drive (fins) electrodes are used for actuation while the motion of the electrode provides changes in capacitance. Due to the constant driving forces involved, a large capacitance tuning range can be obtained. The three dimensional aspect of the device avails large surface area. When large aspect ratio features are provided, a lower actuation voltage can be used. Upon fabrication, the MEMS device is completely encapsulated, requiring no additional packaging of the device. Further, since alignment and bonding can be done on a wafer scale (wafer scale MEMS packaging), an improved device yield can be obtained at a lower cost.
Abstract:
A three-dimensional package consisting of a plurality of folded integrated circuit chips ( 100, 110, 120 ) is described wherein at least one chip provides interconnect pathways for electrical connection to additional chips of the stack, and at least one chip ( 130 ) is provided with additional interconnect wiring to a substrate ( 500 ), package or printed circuit board. Further described, is a method of providing a flexible arrangement of interconnected chips that are folded over into a three-dimensional arrangements to consume less aerial space when mounted on a substrate, second-level package or printed circuit board.
Abstract:
A micro-electromechanical (MEM) RF switch provided with a deflectable membrane (60) activates a switch contact or plunger (40). The membrane incorporates interdigitated metal electrodes (70) which cause a stress gradient in the membrane when activated by way of a DC electric field. The stress gradient results in a predictable bending or displacement of the membrane (60), and is used to mechanically displace the switch contact (30). An RF gap area (25) located within the cavity (250) is totally segregated from the gaps (71) between the interdigitated metal electrodes (70). The membrane is electrostatically displaced in two opposing directions, thereby aiding to activate and deactivate the switch. The micro-electromechanical switch includes: a cavity (250); at least one conductive path (20) integral to a first surface bordering the cavity; a flexible membrane (60) parallel to the first surface bordering the cavity (250), the flexible membrane (60) having a plurality of actuating electrodes (70); and a plunger (40) attached to the flexible membrane (60) in a direction away from the actuating electrodes (70), the plunger (40) having a conductive surface that makes electric contact with the conductive paths, opening and closing the switch.
Abstract:
A micro-electromechanical switch (MEMS) having a deformable elastomeric element (1) which exhibits a large change in conductivity with a small amount of displacement. The deformable elastomeric element (1) is displaced by an electrostatic force that is applied laterally resulting in a small transverse displacement. The transversal displacement, in turn, pushes a metallic contact (7) against two conductive paths (5, 6), allowing passage of electrical signals. The elastomer (1) is provided on two opposing sids with embedded metallic elements (9, 10), such as impregnated metallic rods, metallic sheets, metallic particles, or conductive paste. Actuation electrodes (18, 8) are placed parallel to the conductive sides of the elastomer. A voltage applied between the conductive side of the elastomer and the respective actuation electrodes (18, 8) generate the electrostatic attractive force that compresses the elastomer (1), creating the transverse displacement that closes the MEMS. The elastomeric based MEMS extends the lifetime of the switch by extending fatigue life of the deformable switch elements.
Abstract:
PROBLEM TO BE SOLVED: To improve the high-frequency performance of transistor design, and a manufacturing yield by combining processes from various techniques for eliminating and reducing the source of parasitic capacity. SOLUTION: Collector, base, and emitter regions are formed on a substrate, a second substrate is mounted, an original substrate is completely or partially removed, a non-active collector region is removed or is set to a semi-insulator, and wiring and contact are performed from the original back surface of a chip. A dielectric material used in a manufacturing process is removed, thus further reducing electrostatic capacity. A high-frequency transistor is jointed to a CMOS chip or a wafer, thus forming a BICMOS chip.