STARE: a semiconductor-integrated transmit-array architecture for 6G beamforming

Reconfigurable intelligent surfaces (RIS) are considered a key technology for 6G, but existing implementations based on liquid crystals, PIN diodes, or varactors are limited by slow response, high loss, and costly integration. This study presents the first RIS system directly realized using a standard semiconductor process. The proposed architecture, termed STARE (Semiconductor Transmit Array with Reconfigurable Elements), integrates a custom-designed Selective Overlap Diode (SOD) into high-resistivity silicon, enabling tunable ON resistance and OFF capacitance while maintaining low power operation. A vialess transmit-type unit cell employing magnetic coupling eliminates the need for through silicon vias, thereby simplifying fabrication and reducing substrate losses. Experimental validation demonstrates 180° phase control and beam steering from -45° to +45° at 15.5 GHz. These results establish STARE as the first semiconductor-foundry-manufacturable RIS, bridging device-level fabrication with system-level beamforming and providing a scalable, energy-efficient, and cost-effective solution for future wireless systems.