Abstract:
A semiconductor accelerometer is formed by attaching a semiconductor layer to a handle wafer by a thick oxide layer. Accelerometer geometry is patterned in the semiconductor layer, which is then used as a mask to etch out a cavity in the underlying thick oxide. The mask may include one or more apertures, so that a mass region will have corresponding apertures to the underlying oxide layer. The structure resulting from an oxide etch has the intended accelerometer geometry of a large volume mass region supported in cantilever fashion by a plurality of piezo-resistive arm regions to a surrounding, supporting portion of the semiconductor layer. Directly beneath this accelerometer geometry is a flex-accommodating cavity realized by the removal of the underlying oxide layer. The semiconductor layer remains attached to the handle wafer by means of the thick oxide layer that surrounds the accelerometer geometry, and which was adequately masked by the surrounding portion of the top semiconductor layer during the oxide etch step. In a second embodiment support arm regions are dimensioned separately from the mass region, using a plurality of buried oxide regions as semiconductor etch stops.
Abstract:
An adaptive feedback control method is provided for a chemical mechanical polish process to minimize a dielectric layer clearing time difference between two annular regions on a substrate. An optical system with an optical window passes below the polishing pad and detects reflected light interference signals from at least two annular regions. A pre-clearing time difference is determined and is used to calculate an adjustment to one or both of a CMP head membrane pressure and a retaining ring pressure. The pressure adjustment is applied before the end of the polish cycle to avoid the need for a second polish cycle and to reduce a dishing difference and a resistance difference in a metal layer in the at least two annular regions. In some embodiments, a second pressure adjustment is performed before the end of the cycle and different CMP head membrane pressure adjustments are made in different pressure zones.
Abstract:
The present invention generally relates to the formation of a micro-electromechanical system (MEMS) cantilever switch in a complementary metal oxide semiconductor (CMOS) back end of the line (BEOL) process. The cantilever switch is formed in electrical communication with a lower electrode in the structure. The lower electrode may be either blanket deposited and patterned or simply deposited in vias or trenches of the underlying structure. The excess material used for the lower electrode is then planarized by chemical mechanical polishing or planarization (CMP). The cantilever switch is then formed over the planarized lower electrode.
Abstract:
A method for thinning a wafer layer to a predetermined thickness comprises two phases of thinning. A first thinning phase and a second thinning phase, wherein the first thinning phase is a preparatory thinning phase and the second thinning phase is a final thinning phase, so performed that the structure comprising silicon meets as thinned the final thickness as predetermined. Such thinned layer in a wafer for instance, can be used in a sensor to be used in normal sized, micromechanical or even nano-sized devices for the device specific sensing applications in electro-mechanical devices.
Abstract:
The present invention relates to producing ultra flat micro surfaces suitable, for instance, for micro-mirrors which meet the requirements of diffractive mode operation. In particular, it relates to low pressure chemical mechanical planarization (CMP) of a partially cured sacrificial layer. The method of producing an ultra-flat surface overlying a sacrificial substrate, the sacrificial substrate including a polyimide thin film, includes: thermal partial imidization of a polyamic acid film, wherein at least a portion but not all of the polyamic acid film has been imidized into polymide; chemical mechanical polishing of the partially imidized film; and thermal final imidization of the polished partially iminized film.
Abstract:
One embodiment of the present invention provides a process for selective etching during semiconductor manufacturing. The process starts by receiving a silicon substrate with a first layer composed of a first material, which is covered by a second layer composed of a second material. The process then performs a first etching operation that etches some but not all of the second layer, so that a portion of the second layer remains covering the first layer. Next, the system performs a second etching operation to selectively etch through the remaining portion of the second layer using a selective etchant. The etch rate of the selective etchant through the second material is faster than an etch rate of the selective etchant through the first material, so that the second etching operation etches through the remaining portion of the second layer and stops at the first layer.