Leakage Current Analysis Method for Metal Insulator Semiconductor Capacitors Through Low-Frequency Noise Measurement

Area of Science:

• Semiconductor device physics
• Materials science
• Electrical engineering

Background:

• Thinner gate oxides in complementary metal-oxide-semiconductor (CMOS) devices improve speed but cause significant gate leakage.
• Traditional dielectric analysis methods (I-V, C-V, charge pumping) for leakage current are complex and time-consuming.
• A simpler, highly sensitive method is needed to analyze gate leakage in advanced semiconductor materials.

Purpose of the Study:

• To investigate the effectiveness of low-frequency noise (LFN) measurement for analyzing gate leakage current in metal-insulator-semiconductor (MIS) capacitors.
• To explore the relationship between LFN characteristics and gate leakage current (I_G) in hafnium zirconium silicate (HZS) dielectrics.
• To determine the impact of SiO₂ content on leakage mechanisms and trap densities in HZS MIS capacitors.

Main Methods:

• Fabrication of MIS capacitors using hafnium zirconium silicate (HZS) with varying SiO₂ ratios (x = 0, 0.1, 0.2).
• Characterization using low-frequency noise (LFN) measurements to obtain power spectral density (S_IG).
• Complementary electrical analyses including J-V (current density-voltage) and C-V (capacitance-voltage) measurements.

Main Results:

• A clear correlation was observed between the power spectral density of noise (S_IG) and gate leakage current (I_G).
• Increasing the SiO₂ ratio in HZS (from x=0 to x=0.2) led to a decrease in gate leakage current, confirmed by J-V measurements.
• C-V measurements indicated an increase in oxide-trapped charge (N_ot) with higher SiO₂ content, while LFN analysis revealed reduced trap density as the primary cause for leakage reduction.

Conclusions:

• Low-frequency noise (LFN) measurement is a viable, sensitive, and simple technique for analyzing gate leakage in MIS capacitors.
• The reduction in gate leakage current with increased SiO₂ in HZS dielectrics is attributed to a decrease in the insulator's trap density.
• This study provides a valuable alternative method for characterizing dielectric reliability and leakage in advanced gate insulator materials.