Alpha-particle-induced charge transfer between n+ regions in high-density trench DRAM with isolated p-well structures

Alpha-particle-induced charge transfer (ACT) between n⁺ regions inherent in isolated p-well structures is described. The isolated p-well structures in Si ICs such as advanced trench DRAM cells can cause anomalous charge collection through the ACT. The collected charge is evaluated for advanced trench DRAM cells by circuit and device simulations. In addition, this mechanism is compared to charge transfer in devices with ordinary p-well structures by means of simulations of generalized model structures. It is concluded that ACT with isolated p-well structures may cause a significant problem with scaling, whereas ACT with ordinary p-well structures can be avoided by following a proposed scaling law