Abstract: A semiconductor die is disclosed comprising a lateral semiconductor device on an upper major surface of a substrate, the integrated circuit comprising a silicon layer over the substrate, a recess in the silicon layer, a layer of LOCOS silicon oxide within the recess and having a grown upper surface which is coplanar with the surface of an un-recessed portion of the silicon layer, wherein the silicon layer beneath the recess has a non-uniform lateral doping profile, and is comprised in a drift region of the lateral semiconductor device. A method of making such a die is also disclosed, as is an integrated circuit and a driver circuit.

Abstract: A semiconductor die is disclosed comprising a lateral semiconductor device on an upper major surface of a substrate, the integrated circuit comprising a silicon layer over the substrate, a recess in the silicon layer, a layer of LOCOS silicon oxide within the recess and having a grown upper surface which is coplanar with the surface of an un-recessed portion of the silicon layer, wherein the silicon layer beneath the recess has a non-uniform lateral doping profile, and is comprised in a drift region of the lateral semiconductor device. A method of making such a die is also disclosed, as is an integrated circuit and a driver circuit.

Abstract: There is disclosed a semiconductor device. The device comprises: a silicon layer; a tapered insulating layer formed on the silicon layer; and a plurality of Bipolar CMOS DMOS device layers formed above the tapered insulating layer. The taper of the tapered insulating layer is in the lower surface of the tapered insulating layer. The tapered insulating layer has a substantially planar upper surface and is at least partially recessed in the silicon layer.

Abstract: A resonator comprises a bottom electrode layer (12), a top electrode layer (10) which defines a resonator body; and a piezoelectric layer (14) sandwiched between the top and bottom electrode layers. An external region (152) is provided around the outside of the periphery of the resonator body. The cutoff frequency of a first resonance mode of the external region (152) is matched to the cutoff frequency of a second, different, resonance mode of the resonator body. The invention provides a deliberate change (typically increase) in the cutoff frequency the resonance modes in the external region, so that one of the modes has a cutoff frequency close to the cutoff frequency of the fundamental mode of the resonator body.

Abstract: A resonator comprises a bottom electrode layer (12), a top electrode layer (10) which defines a resonator body; and a piezoelectric layer (14) sandwiched between the top and bottom electrode layers. An external region (152) is provided around the outside of the periphery of the resonator body. The cutoff frequency of a first resonance mode of the external region (152) is matched to the cutoff frequency of a second, different, resonance mode of the resonator body. The invention provides a deliberate change (typically increase) in the cutoff frequency the resonance modes in the external region, so that one of the modes has a cutoff frequency close to the cutoff frequency of the fundamental mode of the resonator body.