Selective atomic layer deposition of HfO2 on copper patterned silicon substrates

Abstract

Selective atomic layer deposition ͑ALD͒ was performed on copper patterned silicon substrates to selectively deposit HfO 2 film on silicon. The selectivity is based on differences of surface physics/ chemistry rather than use of any molecular masking such as self-assembled monolayers. On silicon, the growth rate of HfO 2 is 0.11 nm /cycle with no initial inhibition of film growth, while on copper no HfO 2 deposition was observed up to at least 25 ALD cycles. The selective growth on silicon over copper at 25 ALD cycles provides a patterned film deposition at thicknesses of 2.8 nm HfO 2 which is relevant to semiconductor nanofabrication.

Nanopatterning by Area‐Selective Atomic Layer Deposition

“…No HfO 2 film was formed on the Cu surface up to 25 cycles; beyond 25 cycles, HfO 2 was deposited. This deposition selectivity was attributed to the incubation time of HfO 2 deposition on the Cu surface [91]. In fact, surface-dependent growth has been reported several times in ALD [92][93][94][95].…”

“…The SiH 2 Cl 2 precursor reacts only at NÀH terminated sites, resulting in the growth of SiN x [90]. Recently, AS-ALD HfO 2 was reported on two different surface materials, Si and Cu [91]. No HfO 2 film was formed on the Cu surface up to 25 cycles; beyond 25 cycles, HfO 2 was deposited.…”

Characterization of improved Capacitive Micromachined Ultrasonic Transducers (CMUTS) using ALD high-Κ dielectric isolation

“…To calculate κ and measure E BD of the ALD HfO 2 thin film, we fabricated test capacitors with copper bottom and aluminum top electrodes. Since the nucleation rate of ALD HfO 2 may differ on various material surfaces, affecting its thickness per cycle of deposition [5], we choose to characterize the HfO 2 film on top of a copper bottom electrode to best replicate surface conditions used in the CMUT fabrication process. Both top and bottom electrodes are 1300Å and a 50 nm ALD HfO 2 dielectric layer was deposited using Cambridge Nanotech Fiji F202 system at 250°C.…”

CMUTs with high-K atomic layer deposition dielectric material insulation layer

“…Copper was chosen for the bottom electrode due to the material’s low resistivity and the process similarity to the growth of HfO on copper sacrificial layer during the CMUT fabrication process [40]. Since the nucleation rate of HfO may differ on various material surfaces, affecting its thickness per cycle of deposition [41], the HfO film on top of a copper bottom electrode was characterized to best replicate the surface conditions used in the CMUT fabrication process. Both top and bottom electrodes are 1300 Å and a 50-nm HfO dielectric layer was deposited using a Cambridge Nanotech Fiji F202 system at 250°C.…”