Ion implanted resistors formed in the body of a crystalline silicon substrate. The resistors have a different conductivity type from that of the silicon substrate. The sheet resistance and temperature dependence of the resistor layer is determined by the dose of the implant. Temperature variation can be optimized to be less than 2% over the temperature range −40 C to +85 C.Furthermore, the temperature variation at room temperature (˜25 C) can be reduced to nearly zero.