  We present a wafer trimming technique for producing superconducting
micro-resonator arrays with highly uniform frequency spacing. With the
light-emitting diode (LED) mapper technique demonstrated previously, we first
map the measured resonance frequencies to the physical resonators. Then, we
fine-tune each resonator's frequency by lithographically trimming a small
length, calculated from the deviation of the measured frequency from its design
value, from the interdigitated capacitor. We demonstrate this technique on a
127-resonator array made of titanium-nitride (TiN) and show that the uniformity
of frequency spacing is greatly improved. The array yield in terms of frequency
collisions improves from 84% to 97%, while the quality factors and noise
properties are unaffected. The wafer trimming technique provides an
easy-to-implement tool to improve the yield and multiplexing density of large
resonator arrays, which is important for various applications in photon
detection and quantum computing.
