Thin bidirectional bipolar junction transistor devices from bonded wide and thick wafers

A method for fabricating a thin bidirectional bipolar junction transistor device, comprising:

• activating, with a diffusion process, a first-conductivity-type dopant and a second conductivity-type dopant introduced into different regions on a first side of a first semiconductor wafer;
• reducing a thickness of the first semiconductor wafer by removing a portion of the first semiconductor wafer from a second side of the first semiconductor wafer opposite the first side of the first semiconductor wafer;
• activating, without the diffusion process, the first-conductivity-type dopant and the second conductivity-type dopant introduced into different regions on the second side of the first semiconductor wafer;
• activating, with the diffusion process, the first-conductivity-type dopant and the second conductivity-type dopant introduced into different regions on a first side of a second semiconductor wafer;
• reducing a thickness of the second semiconductor wafer by removing a portion of the second semiconductor wafer from a second side of the second semiconductor wafer opposite the first side of the second semiconductor wafer;
• activating, without the diffusion process, the first-conductivity-type dopant and the second conductivity-type dopant introduced into different regions on the second side of the second semiconductor wafer;
• and
• bonding the first semiconductor wafer to the second semiconductor wafer.

A thin bidirectional bipolar junction transistor device, comprising:

• a first semiconductor wafer including:
• a first front side junction including a first base region and a first emitter/collector region on a first side of the first semiconductor wafer, and
• a first backside junction including a second base region and a second emitter/collector region on a second side of the first semiconductor wafer opposite the first side of the first semiconductor wafer, wherein the first backside junction is thinner than the first front side junction;
• and
• a second semiconductor wafer including:
• a second front side junction including a third base region and a third emitter/collector region on a first side of the second semiconductor wafer, and
• a second backside junction including a fourth base region and a fourth emitter/collector region on a second side of the second semiconductor wafer opposite the first side of the second semiconductor wafer, wherein the second backside junction is thinner than the second front side junction,
• wherein the second side on the first semiconductor wafer is bonded to the second side of the second semiconductor wafer.