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IIT C. Problems of Conventional Porous Materials. Conventional Porous Silica (Template Type). Evaporation. Organic Polymer. Film Destruction. Pore. Heat. Large Pores Open Pores. Mechanical Stress (CMP & Packaging ). Siloxane Polymer. E. High mechanical strength. Low dielectric
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Problems of Conventional Porous Materials Conventional Porous Silica (Template Type) Evaporation Organic Polymer Film Destruction Pore Heat Large Pores Open Pores Mechanical Stress (CMP & Packaging) Siloxane Polymer E High mechanical strength Low dielectric constant Weak Elastic Modulus k Difficult to achieve both compatibility. Low Dielectric Constant
Design Concept of NCS (SOD) Nano-Clustering Silica: NCS Small Pore (Molecular-level Size) Nano-cluster Precursor Heat Cavity Catalyst Compatible! • Molecular-level cavities • Low dielectric constant • Strong combination using catalysts • High mechanical strength
Mechanical Strength & Dielectric Constant k=2.25 15 NCS 10 10 GPa Nano-clustering Material Template-type Porous Silica Elastic Modulus [GPa] 5 0 1 2 3 4 Dielectric Constant Using nano-clustering material, the compatibility of 2.25 and 10 GPa was achieved.
STEM of NCS Films Template Type NCS (Non-template Type) Pore Pore Mean pore diameter > 10 nm Mean pore diameter = 2.8 nm • NCS has smaller pores with more homogeneous distribution. • A decrease in pore diameter seems to be effective in improving film properties.
Comparison in the Leakage Current Results Breakdown Template type 2.3 E-7[A/cm2] 4.6 E-11 [A/cm2] Leakage Current [A/cm2] NCS Good insulation property Electric Field [MV/cm] Pore size reduction gives high insulation property for NCS.
Penetration Test No Penetration Closed Pore Open Pore Penetration ZrN ZrN CVD Porous Low-k Cross-sectional SEM images after depositing ZrN CVD film Deposited film Penetrated layer Low-k film NCS Template type No penetration Penetration depth: 65 nm No open pores in NCS
Film Properties Properties Template Type NCS Average pore size [nm] 11.2 2.8 Dielectric constant ( @1.0 V, 1 MHz ) 2.25 2.25 Leakage current [A/cm2] ( @ 0.2 MV/cm ) 2.3E-7 4.6E-11 Resistance of penetration for CVD ZrN 65nm penetration No penetration Elastic modulus [GPa] 6.0 10 All film properties are improved in NCS. Outstanding film properties • Reduction of pore size • Homogeneous pore distribution Compatibility Low-k High film strength
NCS SiOC Evaluation of Pull Stress Cumulative Probability Plot of Pull Force Pull stress Neck Cumulative Probability [%] No peeling No destruction Pull Force [mN] Cu/NCS multi-level interconnects were strong enough for the packaging process.
Evaluation of Reliability Resistance of the Via-chains Monitors after the Thermal Stress ( 200ºC, 1000h ) As prepared No deterioration After thermal stress ( 200ºC, 1000h ) Cumulative Probability [%] Resistance [ohm] No thermal stress-induced failure was observed.