Cost-Effective Silicon Vertical Diode Switch for Next-Generation Memory Devices

In this letter, a cost-effective vertical diode scheme for next-generation memory devices, including phase-change memories (PCMs), is realized. After the contact formation for diodes with only one mask layer, an amorphous silicon (a-Si) film was deposited within the contacts using SiH4 ramp-up ambient in a conventional batch-type furnace in order to minimize the growth of native oxide. A deposition/etch-back/deposition scheme enabled us to achieve robust vertical diodes without any seams or interfacial oxide layer within the vertical diode pillars. Subsequent annealing at 600 degrees C provided solid-phase epitaxial alignment of the a-Si layer. An ideality factor revealed that the new scheme provided noticeable crystallinity of the silicon diodes. Moreover, the electrical characteristics of the diodes verified that the scheme was suitable for full operation of PCM devices.