Atomic-Layer-Deposition of Sn-Incorporated MoO₂ Films as an Interface Control Layer for High-Performances TiO₂-Based...

Area of Science:

• Materials Science
• Electrical Engineering
• Nanotechnology

Background:

• Scaling dynamic random-access memory (DRAM) to sub-10 nm nodes presents challenges in maintaining cell capacitance and minimizing leakage current.
• Novel electrode materials and engineered interfaces are crucial for high-density memory applications.
• Interface control layers (ICLs) are essential for optimizing dielectric properties in metal-insulator-metal capacitors.

Purpose of the Study:

• To investigate the thermal atomic layer deposition (ALD) of Sn-incorporated MoO_x (TMO) films for use as ICLs in DRAM capacitors.
• To analyze the growth characteristics and interfacial effects of TMO films between TiO₂ and TiN electrodes.
• To evaluate the impact of TMO ICLs on equivalent oxide thickness (EOT) scaling and leakage current density.

Main Methods:

• Thermal atomic layer deposition (ALD) of Sn-incorporated MoO_x (TMO) films using specific Mo and Sn precursors.
• Systematic investigation of TMO film growth, including the interaction between MoO_x and SnO_x subcycles.
• Fabrication and characterization of metal-insulator-metal capacitors with TMO ICLs, varying TMO thickness from 20 nm to 1 nm.

Main Results:

• Controlled Sn incorporation stabilized the monoclinic MoO₂ phase, enhancing thermal and chemical stability with smooth morphology.
• ALD TMO ICLs promoted in situ rutile TiO₂ crystallization (k ≈ 156) and suppressed low-k TiO_xN_y formation, enabling EOT scaling.
• TMO ICLs significantly reduced leakage current density due to their higher work function (4.7-4.8 eV) compared to TiN (4.5 eV).
• Even at 1-2 nm thickness, TMO ICLs achieved an EOT of 0.58 nm and a leakage current density of 2.4 × 10^-7 A/cm².

Conclusions:

• ALD-grown TMO films effectively function as interface control layers in DRAM capacitors.
• TMO ICLs significantly improve capacitance and reduce leakage current, addressing key challenges in DRAM scaling.
• These findings demonstrate the potential of ALD TMO films for next-generation high-density memory applications.