Patent CH-705433-B1 (CH)
Title: Manufacturing micromechanics composite silicon-metal part useful in clock element, comprises manufacturing substrate with upper and lower layers, and selectively etching cavity in upper layer to define pattern in portion of silicon part
Inventor: FIACCABRINO JEAN-CHARLES
IPC: B81C99/00
Filed: 2007-11-16
Abstract: The method comprises manufacturing a substrate (3) comprising an upper layer (5) and a lower layer (7) extending from an intermediate layer (9) made of silicon oxide, selectively etching a cavity in the upper layer to define a pattern in a portion of a first silicon part, continuing the etching of the cavity in the intermediate layer, and forming a first metal layer (63) from a portion of the cavity formed by a lower conductive layer to form a first metal part with a thickness of greater than 6 microns for insulating the first silicon part. The method comprises manufacturing a substrate (3) comprising an upper layer (5) and a lower layer (7) extending from an intermediate layer (9) made of silicon oxide, selectively etching a cavity in the upper layer to define a pattern in a portion of a first silicon part, continuing the etching of the cavity in the intermediate layer, forming a first metal layer (63) from a portion of the cavity formed by a lower conductive layer to form a first metal part with a thickness of greater than 6 microns for insulating the first silicon part, and releasing micromechanical component of metal-silicon composite substrate. The forming step comprises covering a photosensitive resin over the substrate, selectively performing photolithography on the photoresistive resin substrate depending on a predetermined portion of a metal pattern, and depositing the metal layer by plating from an upper surface of the lower conductive layer, which is vertical to the cavity grown from a bottom of the metal layer between the photoresistive resin and the intermediate layer or the upper layer for forming the first metal part in the pattern. The releasing step is carried out by eliminating the photoresistive resin. The lower conductive layer is made of conductive by doping an upper face of the lower layer and depositing a conductive layer. The photoresistive resin protrudes during photolithography of the upper layer of the substrate to continue the formation of the metal layer by plating between projections of the resin to form a second metal part of the micromechanical component above the silicon part. The method further comprises: machining the upper layer of the substrate to level the metal layer coated with the photoresistive resin after the formation step; and forming a second metal layer by electroplating in a portion of the cavity of the lower layer to form a second metal part along a thickness of the lower layer. The cavity in the lower layer of the substrate is etched to form a second silicon part of the micromechanical component according to a shape and a predetermined thickness before the releasing step. The second metal part forming step comprises covering the photoresistive resin beneath the substrate, selectively performing photolithography on the photosensitive resin in a predetermined part of an additional metal unit, and forming the second metal layer by electroplating a bottom of the cavity of the lower layer to form the metal part in the pattern. The photoresistive resin protrudes during photolithography from the lower layer of the substrate to continue the formation of the second metal layer by electroplating to form the second metal part below the second silicon portion. An independent claim is included for a micromechanics part.