Systems and Methods for Bidirectional Device Fabrication
Methods and systems for double-sided semiconductor device fabrication. Devices having multiple leads on each surface can be fabricated using a high-temperature-resistant handle wafer and a medium-temperature-resistant handle wafer. Dopants can be introduced on both sides shortly before a single long high-temperature diffusion step diffuses all dopants to approximately equal depths on both sides. All high-temperature processing occurs with no handle wafer or with a high-temperature handle wafer attached. Once a medium-temperature handle wafer is attached, no high-temperature processing steps occur. High temperatures can be considered to be those which can result in damage to the device in the presence of aluminum-based metallizations.
1 . A method of fabricating a semiconductor device, comprising:
introducing first-conductivity-type dopants into first regions on a first face of a semiconductor mass; introducing second-conductivity-type dopants into second regions on said first face;
attaching a high-temperature handle wafer to said first face;
introducing first-conductivity-type dopants into third regions on a second face of said semiconductor mass which is parallel to said first face;
introducing second-conductivity-type dopants into fourth regions on said second face;
performing a high-temperature diffusion step; whereby said diffusion step diffuses the first-conductivity-type dopants and the second-conductivity-type dopants to desired depths in said semiconductor mass;
performing medium-temperature fabrication steps on said second face;
attaching a medium-temperature handle wafer to said second face;
removing said high-temperature handle wafer; and
performing medium-temperature fabrication steps on said first face.
2 - 248 . (canceled)