NSF Award
9561650
9561650 Rice This Small Business Innovation Research (SBIR) Phase I project will develop a new process for depositing and patterning RuO2 contacts for use in ferroelectric thin film capacitor memory devices such as non-volatile memories (NVRAMs) and ultra-high density dynamic random access memories (DRAMs). RuO2 has been shown to form a good contact with ferroelectric films such as PZT (PbZr1-xTixO3); this leads to substantially lower fatigue, better I-V characteristics, and improved time-dependent breakdown properties compared to PZT devices having metal contacts such as Pt. However, the lack of a convenient processing technology has impeded the implementation of RuO2 contacts in practical devices. The new process incorporates two key innovations: first, the RuO2 films will be deposited as metallorganic precursors by a spin-on process, and patterned by wet chemical methods before firing. This will enable a simpler, less damaging, and less expensive process than plasma etching, which is the only current method in use for patterning RuO2. Second, the metallorganic precursor will possess organic groups which are photochemical crosslinkable. The process will allow photolithographic patterning of the conductive oxide contact without requiring the use of a separate resist, thus saving process steps. Phase I will develop soluble precursors to RuO2 having organic substituents capable of UV crosslinking, deposit these materials on substrates by a spin-on process, demonstrate photolithographic patterning, and assess the quality of fired RuO2 contacts. This development will enable the practical fabrication of advanced ferroelectric thin film devices with superior performance compared to the current state-of-the-art. Commercial applications of the proposed technology include non-volatile memories for smart cards and pagers, and gigabit-scale DRAMs for computer applications.
