Effect of ALD Processes on Physical and Electrical Properties of HfO₂ Dielectrics for the Surface Passivation of a CMOS Image Sensor Application

Abstract

The surface passivation of a CMOS image sensor (CIS) is highly beneficial for the overall improvement of a device performance. We employed the thermal atomic layer deposition (T-ALD) and plasma enhanced (PE-ALD) techniques for the deposition of 20 nm HfO2 as well as stacked with 3 and 5 nm Al2O3 thin films. The HfO2/Si and Al2O3/HfO2/Si metal-oxide-semiconductor structures were used to analyze the fixed charge density (Qf) and interface trap density (Dit). The as-synthesized samples show high Dit and Qf values (10 12 cm -2 eV -1 ) and a minority carrier lifetime of 15-300 µs. The finite-difference time-domain simulation of high-k dielectrics confirmed that the Al2O3 (top)/HfO2 stacked structures expected higher quantum efficiency for CIS application. The effect of vacuum annealing (VA) and forming gas annealing (FGA) treatments succeeded with the decomposition of the Dit and increase in carrier lifetime. The H2 ambient FGA samples showed a remarkable decrease in the Dit values. To improve the overall performance of the device after passivation, we employed an Al2O3/HfO2 bilayer structure, which showed a low Dit of 10 11 cm -2 eV -1 and a minority carrier lifetime of ~3,700 µs after 400 °C and 30 min FGA. We believe that this surface passivation strategy will pave way for future CIS technology regarding the development of lower defective surface and superior performance.

Metal-Induced Trap States: The Roles of Interface and Border Traps in HfO2/InGaAs

“…Instead, this trap and border trap are considered as a single object. Additionally, a negative interface fixed charge of around 5.0 × 10 11 cm −2 to 1.5 × 10 12 cm −2 , similar to that in a recent study, is included [ 44 ]. The interface fixed charges are related to the incorporation of nitrogen in high-k dielectrics during ALD deposition or in post-deposition treatment [ 45 , 46 ].…”

Recent progress in energy, environment, and electronic applications of MXene nanomaterials

“…To analyze the change in different parameters of air, water, the human body, industrial processes, etc ., different kinds of sensor can be used. 143 In the case of pollution monitoring, diagnosis, air quality control, and breath analysis, gas sensors are valuable assets. 144 On the other hand, the need for a strain sensor is extreme to detect cyclic strains in daily movements.…”

Curing Process on Passivation Layer for Backside-Illuminated CMOS Image Sensor Application

“…In the second experiment, in the absence of SiO 2 , Al 2 O 3 was replaced with HfO 2 in the structure used in the first experiment. HfO 2 films were deposited on a p-type Si substrate used in the first experiment by PEALD using a tetrakisethyl-methylamino hafnium (TEMAHf, Hf[N(CH 3 )C 2 H 5 ] 4 ) precursor with O 2 plasma at a substrate temperature of 280 • C [24]. The thickness of the HfO 2 film was fixed at 20 nm.…”