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Selective Chemistry of Metal Oxide Atomic Layer Deposition on Si Based Substrate Surfaces

  • Author(s): Guo, Lei
  • Advisor(s): Zaera, Francisco
  • et al.

A versatile home-made atomic layer deposition (ALD) reactor was designed and built in our lab. This reactor can be used to deposit metal oxides on both wafer substrates and porous inorganic particles. Also, a simple procedure for selective ALD has been developed for the processing of silicon wafers in order to facilitate the spatially resolved growth of thin solid films on their surfaces. Specifically, a combination of silylation and UV/ozonolysis was tested as a way to control the concentration of the surface hydroxo groups required for subsequent atomic layer deposition (ALD) of metals or oxides. Water contact angle measurements were used to evaluate the hydrophilicity/hydrophobicity of the surface, a proxy for OH surface coverage, and to optimize the UV/ozonolysis treatment. Silylation with silanes was found to be an efficient way to block the hydroxo sites and to passivate the underlying surface, and UV/O3treatments were shown to effectively remove the silylation layer and to regain the surface reactivity. Both O3 and 185 nm UV radiation were determined necessary for the removal of the silylation layer, and additional 254 nm radiation was found to enhance the process. Attenuated total reflection-infrared absorption spectroscopy was employed to assess the success of the silylation and UV/O3 removal steps, and atomic force microscopy data provided evidence for the retention of the original smoothness of the surface. Selective growth of HfO2 films via TDMAHf + H2O ALD was seen only on the UV/O3 treated surfaces; total inhibition of the deposition was observed on the untreated silylated surfaces. We believe that the silylation-UV/O3 procedure advanced here could be easily implemented for the patterning of surfaces in many microelectronic applications.

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