Abstract: Manufacturing a power transistor by forming a gate structure on a first layer, forming a trench in the first layer, self aligned with the gate structure, and forming part of the transistor in the trench. By forming a spacer next to the gate, the spacer and gate can be used as a mask when forming the trench, to allow space for a source region next to the gate. The self-aligning rather than forming the gate after the trench means the alignment is more accurate, allowing size reduction. Another aspect involves forming a trench in a first layer, filling the trench, forming a second layer on either side of the trench with lateral overgrowth over the trench, and forming a source region in the second layer to overlap the trench. This overlap can enable the chip area to be reduced.

Abstract: A semiconductor device has a substrate (50), a buried layer (55), an active area extending from a surface contact to the buried layer, an insulator (130) in a first trench extending towards the buried layer, to isolate the active area, and a second insulator (130) in a second deep trench and extending through the buried layer to isolate the buried layer and the active area from other parts of the substrate. This double trench can help reduce the area needed for the electrical isolation between the active device and the other devices. Such reduction in area can enable greater integration or more cells in a multi cell super-MOS device, and so improve performance parameters such as Ron. The double trench can be manufactured using a first mask to etch both trenches at the same time, and subsequently using a second mask to etch the second deep trench deeper.

Abstract: The present invention is related to a method of processing a high voltage p++/n-well junction on a substrate comprising at least one n-well region and at least one p-well region. The method comprises performing a p-type implantation in a zone surrounding said high voltage p++/n-well junction independently from other implantation.