access icon free Switching operation improvement of phase change memory with nanoscale W plug structure by CMP process

To reduce the reset current for developing reliable high-density phase change random access memory, small bottom electrode contact (BEC) size formation is a critical process. One of the failure modes for the process is the corrosion of the tungsten (W) plug, which is caused by the W chemical mechanical polisher (CMP) process. An ultra-smooth surface of BEC nanoscale W plug structure was successfully fabricated by the CMP process, which reduced the W/phase change material (Ge2Sb2Te5, GST) contact resistance, and gained more homogeneous resistance distribution. Thus, the stability of the device was improved greatly by the acidic buff CMP process compared with that of the device with alkali buff owing to the reduction of W/GST connect resistance fluctuation.

Inspec keywords: antimony compounds; failure analysis; germanium compounds; phase change memories; electrochemical electrodes; chemical mechanical polishing; contact resistance; corrosion protection

Other keywords: CMP process; phase change material; GST; ultra-smooth surface; chemical mechanical polisher process; corrosion; small bottom electrode contact; switching operation; BEC size formation; Ge2Sb2Te5; contact resistance; phase change random access memory; homogeneous resistance distribution; failure modes; BEC nanoscale W plug structure

Subjects: Memory circuits; Electrical contacts; Reliability; Surface treatment (semiconductor technology); Semiconductor storage

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