Silicon photonics have progressed to a point where the next step for commercialization depends on the accessibility of manufacturing foundries. The implementation of a fabless foundry model using standardized process technology platforms is crucial for that to occur. Research and development (R&D) foundries are beginning to play bigger roles in transforming silicon photonics into a mature technology for mass production. R&D foundry services such as multi-project wafer (MPW) shuttles, customized process developmental runs and small volume manufacturing are discussed. The development of commercial foundries for low cost, high volume production is also shown to be underway, and key results from an on-going effort to set-up a manufacturing silicon photonics foundry line are presented.