Thin-film resistor (TFR) formed under a metal layer and method of fabrication

A method for manufacturing a thin film resistor (TFR) module includes forming a TFR element over a substrate; annealing the TFR element to reduce the temperature coefficient of resistance (TCR) of the TFR element; and after forming and annealing the TFR element, forming a pair of conductive TFR heads in contact with the TFR element. By forming the TFR element before the TFR heads, the TFR element may be annealed without affecting the TFR heads, and thus may be formed from various materials with different annealing properties, e.g., SiCCr and SiCr. Thus, the TFR element may be annealed to achieve a near 0 ppm TCR, without affecting the later-formed TFR heads. The TFR module may be formed using a damascene CMP approach and using only a single added mask layer. Further, vertically-extending "ridges" at edges of the TFR element may be removed or eliminated to further improve the TCR performance.