本論文利用0.18 μm CMOS標準製程結合微機電(MEMS)製程形成一側面照光之850 nm矽光檢測器；結構乃使用標準製程形成一水平式光檢測器，再利用微機電製程蝕刻至元件邊緣，使其露出照光面，並利用透鏡式光纖(lensed fiber)直接照射至元件主動層。與傳統之垂直照光式光檢測器比較，可證實側面照光之方式確實降低了基板區因入射光所形成的擴散載子，進而大幅提升元件之頻寬。3-dB頻寬的改善可由垂直照光光檢測器之0.9 GHz提升至側面照光元件之3.4 GHz。 利用思發科技公司之二維元件模擬軟體模擬證明，降低基板區之照光量，可改善擴散載子成份造成的頻率響應滑落(roll-off)情形，達到提升頻寬的效果。另外，本論文針對側面照光光檢測器之尺寸進行分析，因為850 nm波長之光的穿透深度(penetration depth)僅有約20 μm，故當元件之主動區長度較長時，雖然其響應度會增加，但其頻寬值卻會下降。當元件之主動區長度為20 μm時，其頻寬值可改善至5.4 GHz。 This study examines edge-illuminated silicon photodiodes (PDs) fabricated with standard CMOS technology operating at 850-nm wavelength. A micro-electro-mechanical systems process (MEMS) is employed to expose the illuminated surface and achieve edge illumination. A single-mode lensed fiber is employed to inject light into the depletion region of the PD directly, limiting and reducing the diffusive carriers within the bulk Si substrate. Using this procedure achieves greater performance in 3-dB bandwidth than the vertically illuminated PD in this study. The 3-dB bandwidth for the vertically illuminated PD is only 0.9 GHz because of the critical diffusion component. However, the diffusion component generated in the bulk Si substrate is reduced, the 3-dB bandwidth for the edge-illuminated PD is improved to 3.4 GHz. Moreover, Silvaco TCAD simulation is used to verify that the diffusion roll-off could be improved by reducing the diffusion component of photocurrent. Finally, the characteristics of the different size edge-illuminated PDs are investigated. When the length of PD’s active region is longer than 20 μm, the 3-dB bandwidth will degrade. It’s because the penetration depth of the 850 nm-wavelength light into Si is less than 20 μm. The best 5.4 GHz high bandwidth is obtained from an edge-illuminated PD with a 20 μm ×15.6 μm active region.
