Post-Fabrication Trimming of Silicon Ring Resonators via Integrated Annealing

We report post-fabrication trimming of silicon-on-insulator micro-ring resonators via annealing of lattice defects using integrated micro-heaters. Defects are introduced via an inert MeV boron ion implantation at doses ranging from $3\times 10^{10}$ to $3\times 10^{13}$ cm−2. Ion implantation results in a stable red-shift ranging from 20 to 1200 pm, for the stated dose range. Post-implantation annealing produces a subsequent blue-shift ranging from 380 to 800 pm, dependent on the implantation dose, indicating partial recovery of the silicon lattice through removal of the implantation-induced defects. Moreover, evidence is shown for a resonance blue-shift associated with modification of the micro-ring, even without a prior ion implantation step. With the method described in this letter, we demonstrate precise trimming of a four-ring filter such that the resonances are separated by 50 GHz, despite the as-fabricated rings having a random resonance separation resulting from fabrication variances.