A device and a method of forming the device are disclosed. The device includes
a reflector, a first dielectric layer disposed on the reflector, and a thin film
resistor disposed on the reflector. The reflector acts as a barrier between the
thin film resistor and an underlying dielectric layer which may have a non-uniform
thickness. Thus, the thickness control and uniformity of the dielectric layer underlying
the reflector does not affect the laser trimming of the thin film resistor. In
addition to serving as a barrier, the reflector reflects the trimming laser energy
back towards the thin film resistor, thereby improving the efficiency of the laser
trimming of the thin film resistor. Furthermore, the thickness of the first dielectric
layer situated below the thin film resistor and above the reflector can be easily
controlled to substantially optimize the laser trimming efficiency of the thin
film resistor.
