100 may be fabricated over the silicon area of a semiconductor chip in contrast to conventional resistor trimming processes the resistor 36 may be adjusted during operation of the chip conventional trimming processes occur before a chip is diced and packaged the embodiments of the present invention allow for adjustment of resistance after a chip is diced and packaged fig2 a 9 illustrate further aspects of the present invention and are discussed in detail below fig2 a and 2b illustrate an embodiment of a tunable resistor 40 and associated elements fig2 a is a top plan view and fig2 b is a section view taken on line 2 b u2014 2 b fig2 a and 2b generally illustrate an embodiment of the resistor 40 as formed by a damascene process a dielectric 50 separates the resistor 40 from a heater 60 in fig2 a and 2b the resistor 40 is disposed within the dielectric 50 which is in turn disposed within the heater 60 the heater 60 is attached to conductive leads 62 64 at contacts 66 68 respectively the conductive leads 62 64 may be electrically connected to a heater driver circuit not illustrated such as the circuit 10 illustrated in fig1 the heater driver circuit provides a heating current to the heater 60 the heater 60 may comprise for example a resistive element that generates heat when a current passes therethrough the leads 62 64 may extend u201c vertically u201d a direction perpendicular to the page in fig2 a to contact the heater 60 conductive leads 42 44 may similarly extend.