Centura® DPN HD Gate Stack
The Centura DPN HD (high dose) system consists of plasma nitridation and post-nitridation anneal (PNA) chambers integrated on the Centura mainframe. It extends the nitridation capabilities of the DPN product portfolio for the dynamic random access memory (DRAM) peripheral gate and complements Applied’s long-standing, leading-edge nitridation technology for logic devices.
In the DPN HD nitridation process, silicon oxide dielectric is infused with nitrogen using low-energy, pulsed plasma to create the desired high nitrogen concentration at the oxynitride/poly interface and low concentration at the silicon/oxynitride interface of the gate stack for preserving high channel mobility. New chemistry and direct, high-temperature wafer heating generate the higher dosages of nitrogen needed for oxynitride gates at the 3X and 2Xnm nodes while simultaneously achieving superior leakage and threshold voltage performance. Conventional nitridation processes are limited in achieving the requisite leakage and threshold voltage.
Nitrogen concentration in the oxynitride decreases over time following the nitridation treatment. Because the DPN HD system integrates PNA and DPN chambers in a single vacuum environment, the system can counteract this nitrogen loss by performing a high-temperature anneal immediately following the nitridation process. In addition, integrating the plasma nitridation and PNA chambers on a common platform removes time-dependent process variability, producing a more stable and robust process essential for manufacturing oxynitride gates. The PNA also eliminates an unstable bonding phase from the nitridation process that can cause variation in threshold voltage. By reducing or removing this unstable phase, the PNA contributes to improved device performance.