We present in situ topographical observations of film growth during the initial cycles of atomic layer deposition (ALD) using scanning tunneling microscopy (STM). We present cycle-by-cycle STM topographs of zinc sulfide films during ALD on Au(111) surfaces, tracking individual grains, 5 nm in diameter, as they grow over tens of cycles. We find that grain morphology is temperature-dependent and grain size increases with deposition temperature from 100 to 160 °C.

We have built a combined scanning tunneling microscope-atomic layer deposition (STM-ALD) tool that performs in situ imaging of deposition. It operates from room temperature up to 200 °C, and at pressures from 1 × 10(-6) Torr to 1 × 10(-2) Torr. The STM-ALD system has a complete passive vibration isolation system that counteracts both seismic and acoustic excitations. The instrument can be used as an observation tool to monitor the initial growth phases of ALD in situ, as well as a nanofabrication tool by applying an electric field with the tip to laterally pattern deposition. In this paper, we describe the design of the tool and demonstrate its capability for atomic resolution STM imaging, atomic layer deposition, and the combination of the two techniques for in situ characterization of deposition.