This paper presents a SEU hardening approach that uses a dummy collector to reduce charge collection in the main transistor. The dummy collector is obtained using the silicon space between adjacent HBTs. It is obtained without any process modification or area penalty. The simulations are performed for normal and angled strikes. The hardened device shows significant reduction in charge collection due to sharing of diffusive charge collection by the dummy collector. Multiple HBT arrays of regular and hardened HBT are simulated to study the simultaneous charge collection in multiple HBTs. With hardening, charge collection in multiple devices is suppressed considerably for normal and angled strikes as the shared dummy collector collects a large amount of charge.