In‐Cycle Helium Plasma Integrated Atomic Layer Deposition Process for Screening Effect Alleviation and Performance Enhancement in a‐IGZO TFTs

Abstract Amorphous indium gallium zinc oxide (a‐IGZO) grown by atomic layer deposition (ALD) is a promising channel material for next‐generation dynamic random‐access memory (DRAM), owing to its excellent electrical properties. In ALD processes for a‐IGZO, gallium and zinc precursors—trimethylgallium (TMGa) and diethylzinc (DEZ), respectively—possess small ligands and are widely regarded as screening effect‐free precursors. In contrast, the indium precursor [3‐(dimethylamino)propyl]‐dimethyl indium (DADI) contains bulky ligands that induce a screening effect, which impedes the self‐limiting surface reactions essential to ALD. Here, we report an in‐cycle helium plasma integrated ALD process, termed screening effect alleviated ALD (SEA‐ALD), which increases the growth per cycle (GPC) from 0.8 to 1.0 Å in In 2 O 3 films. Helium ions promote surface migration of DADI, remove residual ligands, and generate oxidative radicals, thereby reducing the oxygen vacancy fraction from 46.3% to 15.8%. With SEA‐ALD, a‐IGZO transistors achieve a mobility of 60.6 cm 2 V −1 s −1 , a subthreshold swing of 75.4 mV dec −1 , and an on/off ratio > 10 9 without post‐annealing. A resistor‐loaded inverter exhibits full‐swing characteristics and a gain of 22 at V DD = 2 V. Moreover, SEA‐ALD offers a general route to overcoming precursor‐inherent screening effects, thereby expanding the precursor design window and increasing the number of viable precursor candidates for ALD.