HfO2 and SiO2 etch rates as a function of the self-bias power. Process condition: SiCl4/Cl2 mixture (50/75 sccm) at 5 mTorr and 1000 W rf inductive power. Negative values indicate that SiClx polymer deposition takes place on the wafer (no etching) and provides the deposition rate.
XPS analysis of a HfO2(10 nm)/SiO2(0.7 nm)/Si stack: (a) before etching; (b) after the partial etching of the HfO2 layer by a SiCl4(50 sccm)/Cl2(75 sccm) plasma at 5 mTorr with 1000 W ICP power and 30 W bias power; and (c) after an overetch period of 4 seconds on the SiO2 underlayer.
HfO2 and SiO2 etch rates as a function of the Cl2 gas flow rate in the SiCl4 plasma. Process condition: SiCl4/Cl2 mixture (50/X sccm) at 5 mTorr and 1000 W rf inductive power and 30 W rf bias power.
FIB-STEM cross section of a typical metal gate stack made of a SiO2/SiN hard mask, a Si/TiN metal gate and an HfSiON/SiON gate dielectric. (a) before HfSiON etching; (b) after HfSiON etching in BCl3 plasma chemistry; (c) after HfSiON etching in the SiCl4/Cl2 chemistry (150 sccm of SiCl4 with condition of Fig. 2); (d) after HfSiON etching in SiCl4/Cl2 and HF dip.
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