Abstract:
A method is disclosed for forming a micromechanical device. The method includes fully or partially forming one or more micromechanical structures multiple times on a first substrate. A second substrate is bonded onto the first substrate so as to cover the multiple areas each having one or more micromechanical structures, so as to form a substrate assembly. The substrate assembly is then separated into individual dies, each die having the one or more micromechanical structures held on a portion of the first substrate, with a portion of the second substrate bonded to the first substrate portion. Finally, the second substrate portion is removed from each die to expose the one or more micromechanical structures on the first substrate portion. The invention is also directed to a method for forming a micromechanical device, including: forming one or more micromechanical structures in one or more areas on a first substrate; bonding caps onto the first substrate so as to cover the one or more areas each having one or more micromechanical structures, so as to form a substrate assembly; after a period of time, removing the caps to expose the one or more micromechanical structures. During the period of time between bonding the caps and later removing the caps, the substrate assembly can be singulated, inspected, irradiated, annealed, die attached, shipped and/or stored.
Abstract:
A method for forming a MEMS device is disclosed, where a final release step is performed just prior to a wafer bonding step to protect the MEMS device from contamination, physical contact, or other deleterious external events. Without additional changes to the MEMS structure between release and wafer bonding and singulation, except for an optional stiction treatment, the MEMS device is best protected and overall process flow is improved. The method is applicable to the production of any MEMS device and is particularly beneficial in the making of fragile micromirrors.
Abstract:
A spatial light modulator is disclosed, along with a method for making such a modulator that comprises an array of micromirror devices. The center-to-center distance and the gap between adjacent micromirror devices are determined corresponding to the light source being used so as to optimize optical efficiency and performance quality. The micromirror device comprises a hinge support formed on a substrate and a hinge that is held by the hinge support. A mirror plate is connected to the hinge via a contact, and the distance between the mirror plate and the hinge is determined according to desired maximum rotation angle of the mirror plate, the optimum gap and pitch between the adjacent micromirrors. In a method of fabricating such spatial light modulator, one sacrificial layer is deposited on a substrate followed by forming the mirror plates, and another sacrificial layer is deposited on the mirror plates followed by forming the hinge supports. The two sacrificial layers are removed via the small gap between adjacent mirror devices with spontaneous vapor phase chemical etchant. Also disclosed is a projection system that comprises such a spatial light modulator, as well as a light source, condensing optics, wherein light from the light source is focused onto the array of micromirrors, projection optics for projecting light selectively reflected from the array of micromirrors onto a target, and a controller for selectively actuating the micromirrors in the array.
Abstract:
A spatial light modulator is disclosed, along with methods for making such a modulator, that comprises an array of micromirrors each having a hinge and a micromirror plate held via the hinge on a substrate, the micromirror plate being disposed in a plane separate from the hinge and having a diagonal extending across the micromirror plate, the micromirror plate being attached to the hinge such that the micromirror plate can rotate along a rotation axis that is parallel to, but off-set from the diagonal of the micromirror plate. Also disclosed is a projection system that comprises such a spatial light modulator, as well as a light source, condensing optics, wherein light from the light source is focused onto the array of micromirrors, projection optics for projecting light selectively reflected from the array of micromirrors onto a target, and a controller for selectively actuating the micromirrors in the array.
Abstract:
An etching method, such as for forming a micromechanical device, is disclosed. One embodiment of the method is for releasing a micromechanical structure, comprising, providing a substrate; providing a sacrificial layer directly or indirectly on the substrate; providing one or more micromechanical structural layers on the sacrificial layer; performing a first etch to remove a portion of the sacrificial layer, the first etch comprising providing an etchant gas and energizing the etchant gas so as to allow the etchant gas to physically, or chemically and physically, remove the portion of the sacrificial layer; performing a second etch to remove additional sacrificial material in the sacrificial layer, the second etch comprising providing a gas that chemically but not physically etches the additional sacrificial material. Another embodiment of the method is for etching a silicon material on or within a substrate, comprising: performing a first etch to remove a portion of the silicon, the first etch comprising providing an etchant gas and energizing the etchant gas so as to allow the etchant gas to physically, or chemically and physically, remove the portion of silicon; performing a second etch to remove additional silicon, the second etch comprising providing an etchant gas that chemically but not physically etches the additional silicon.
Abstract:
The etching of a sacrificial silicon portion in a microstructure such as a microelectromechanical structure by the use of etchant gases that are noble gas fluorides or halogen fluorides is performed with greater selectivity toward the silicon portion relative to other portions of the microstructure by the addition of non-etchant gaseous additives to the etchant gas. An additional discovery is that non-etchant gaseous additives that have a molar averaged formula weight that is below that of molecular nitrogen offer significant advantages over gaseous additives of higher formula weights by causing completion of the etch in a shorter period of time while still achieving the same improvement in selectivity.
Abstract:
The present invention discloses a method and apparatus for removing the sacrificial materials in fabrications of microstructures using a vapor phase etchant recipe having a spontaneous vapor phase chemical etchant. The vapor phase etchant recipe has a mean-free-path corresponding to the minimum thickness of the sacrificial layers between the structural layers of the microstructure. This method is of particular importance in removing the sacrificial layers underneath the structural layers of the microstructure.
Abstract:
A method for forming a MEMS device is disclosed, where a final release step is performed just prior to a wafer bonding step to protect the MEMS device from contamination, physical contact, or other deleterious external events. Without additional changes to the MEMS structure between release and wafer bonding and singulation, except for an optional stiction treatment, the MEMS device is best protected and overall process flow is improved. The method is applicable to the production of any MEMS device and is particularly beneficial in the making of fragile micromirrors.
Abstract:
A micro-mirror that comprises a substrate, a hinge structure formed on the substrate and a mirror plate attached to the hinge structure is provided for use in display systems. The mirror plate is capable of rotating from a non-deflected resting state to a state that is at least 14° degrees. In operation, the micro-mirror switches between an “ON”-state and “OFF”-state, which are defined in accordance with a rotational position of the mirror plate. The OFF state can be a non-deflected position of the micro-mirror (generally parallel to the substrate), the same angle (though opposite direction) as the ON state, or an angle less than the ON state (though in the opposite direction). Reflected light from the “ON” and “OFF” states are thus separated and the contrast ratio is improved.
Abstract:
A projection system, a spatial light modulator, and a method for forming a micromirror array such as for a projection display are disclosed. The spatial light modulator can have two substrates bonded together with one of the substrates comprising a micro-mirror array. The two substrates can be bonded at the wafer level after depositing a getter material and/or solid or liquid lubricant on one or both of the wafers if desired. In one embodiment of the invention, one of the substrates is a light transmissive substrate and a light absorbing layer is provided on the light transmissive substrate to selectively block light from passing through the substrate. The light absorbing layer can form a pattern, such as a frame around an array of micro-mirrors.