Characteristics of ALD High-x HfAlO_x Nanocrystals in Memory Capacitors Annealed at High Temperatures

摘要

Major challenges in transistor gate stack materials include the replacement and SiON dielectrics with high-K dielectric materials, and that of doped polycrystalline Si gate electrodes with metals (1). High-K charge trapping layers are needed in the semiconductor industry for future nano-scale nonvolatile memory (NVM) device applications (2, 3). A ternary system, such as a high-temperature crystalline system of HfAlOx is another approach to obtain a new high-K material due to expectations that the ternary system may provide a new function and alleviate disadvantages of the binary one. A high-K HfO_2/HfAlO/HfO_2 nanolaminate charge trapping layer in a p-Si/SiO_2/HfO_2 /Al_2O_3/Pt memory capacitor has been investigated. The HfO_2 film is shown to be fully polycrystalline grain, while the Al_2O_3 film shows a partial crystalline grain after the PDA treatment. It is observed that the Al_2O_3/HfO_2/Al_2O_3 middle layers are mixed together after PDA treatment, resulting in a partially crystalline HfAlO_x layer.