Cyclic Plasma Treatment during ALD Hf_1-xZr_xO₂Deposition

Abstract

Effect of slot plane antenna (SPA) Ar plasma on the reliability of intermediate plasma (DSDS) treated ALD Hf1-xZrxO2 samples with x = 0, 0.31, 0.8 were investigated. The metal oxide semiconductor capacitors (MOSCAP) were subjected to a constant field stress of 27.5 MV/cm in the gate injection mode and the stress-induced flatband voltage shifts and stress induced leakage currents were monitored. The dielectric film deposited without any intermediate step (As-Dep), having the same number of atomic layer deposition (ALD) cycles as DSDS samples was used as the control sample. It was observed that plasma exposure enhances the quality of high-κ film by reducing the number of intrinsic traps in the film and Zr addition further enhances the reliability. Breakdown characteristics also confirm this behavior. Electron affinity variation in HfO2 and ZrO2 and Zr variation seems to contribute to the improvement in DSDS Hf1-xZrxO2 (x = 0.8) by suppressing the oxide trap formation as observed in the Weibull characteristics. DSDS Hf1-xZrxO2 with x = 0.8, therefore, demonstrates a superior equivalent oxide thickness (EOT) downscaling ability and good reliability performance.

Post Plasma Oxidation Processed ALD Al2O3/Hf1-xZrxO2Thin Films on Ge Substrates: Reliability

“…18 This is further enhanced by SPA plasma, which helps to produce a densification of dielectric films with smoother interface. 4,19 Furthermore, it is believed that thin GeO x -type interfacial layer is formed. Therefore, with the addition of Zr in HfO 2 from 0% to 75%, an increase in the accumulation capacitance ( Fig.…”

“…Because of low electron affinity, Zr ions get most of the benefits. 4 The slight increase in interface state density with Zr addition up to 75% can be explained by the EOT downscaling behavior of this dielectrics. It is known that the reduction in film thickness slightly increases the interface state density because of increased stress on the interface.…”

“…In addition, high Zr content in the dielectrics benefits from SPAO because of the lower electron affinity of Zr compared to Hf. 4 It can be further noted that the SPA plasma exposure helps better film densification with reduced impurity concentration in the dielectrics. Additionally, SPAO plasma enhances the formation of atomically flat and smoother dielectric surfaces and interfaces.…”

“…10 Slot-plane-antenna (SPA) plasma treatment has been shown to enhance the CVD and ALD grown oxides quality and reliability along with better interfacial layer properties when the films were exposed to SPA plasma during or after the deposition. 4,[11][12][13] The SPA process provides high density plasma (∼10 12 cm −3 ) at low electron temperature (0.7∼1.5 eV) with a wide process window (7∼1000 Pa) to enable a low damage plasma process compared to conventional inductively coupled plasma (ICP) or electron cyclotron resonance (ECR) plasma. 14 Recently, the use of slot-plane-antenna plasma oxidation (SPAO) has been studied for TiN/ZrO 2 /Al 2 O 3 /Ge MOS capacitors, where SPAO has been introduced in different stages (before Al 2 O 3 deposition, in between Al 2 O 3 and ZrO 2 deposition, and after the deposition of both Al 2 O 3 and ZrO 2 ) during the gate stack formation.…”

High Dielectric Constant Materials for Nanoscale Devices and Beyond

“…51 Zr incorporation in HfO 2 along with intermediate treatment like plasma exposure or plasma oxidation seems to be promising. The time dependent dielectric breakdown (TDDB) characteristics suggest that the time to breakdown of Hf 1-x Zr x O 2 on silicon increases with increasing Zr percentage when the dielectric is exposed to alternate inert plasma during cyclic ALD deposition.…”