A vertical trench etched several microns deep into the silicon extending into a buried diffusion region is used to confine a vertical interconnect element. This element can be a high resistivity undoped polycrystalline silicon load resistor, a medium resistivity doped polycrystalline silicon load resistor,...http://www.google.fr/patents/US4933739?utm_source=gb-gplus-shareBrevet US4933739 - Trench resistor structures for compact semiconductor memory and logic devices
Trench resistor structures for compact semiconductor memory and logic devices
