2026 Wang SnOx Transistor CFET Integration

The development of high-performance p-type oxide semiconductors is essential for realizing complementary logic for monolithic 3D integration, yet p-type oxide semiconductors still exhibit substantially inferior performance compared with their n-type counterparts. In this work, we demonstrate high-performance p-type SnOx transistors by atomic layer deposition (ALD), as back-end-of-line compatible devices for monolithic 3D integration. The SnO x transistors exhibit high field-effect mobility (μFE) of 6.9 cm2/V· s, low subthreshold swing (SS) of 185 mV/dec, decent on/off ratio (ION/IOFF) of 1.8× 104 and high bias stability. By scaling the channel length down to 80 nm, a high on-current (ION) of 38.7 μA/μm at VDS of -1 V is achieved. It is understood that precursor and reaction engineering to suppress Sn4+ component in SnO x film are the key for performance enhancement. Furthermore, a complementary field-effect transistor with ALD SnOx p-FET vertically stacking on ALD In2O3 n-FET is also demonstrated, achieving maximum voltage gain of 21 V/V at VDD of 4 V. These findings suggest ALD SnO x as a promising candidate for scaled high-performance BEOL p-type transistors.